Solar floatovoltaics lit review

Readers Please!!

Any comments are welcome on the discussion page including additional resources/papers/links etc. Papers can be added to relevant sections if done in chronological order with all citation information and short synopsis or abstract. Thank You.

This section includes journal paper review for a project aimed at design and implementation of floating solar PV system (Flotovoltaics) for potential areas such as California Aqueduct, adding towards a sustainable practice of saving water and aquatic life. The need for floatovoltaics arises in places with water deficit or deal with land use issues such as in populous places. Various subsections under this are explained with highlights and key points which may be useful in designing this work.

This literatture review supported the following publications:

• Pierce Mayville, Neha Vijay Patil and Joshua M.Pearce. Distributed manufacturing of after market flexible floating photovoltaic modules. Sustainable Energy Technologies and Assessments. 42, 2020, 100830. https://doi.org/10.1016/j.seta.2020.100830 open access
• Hayibo, K.S.; Mayville, P.; Kailey, R.K.; Pearce, J.M. Water Conservation Potential of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics. Energies 2020, 13, 6285. https://doi.org/10.3390/en13236285 [ open access]
• Hayibo, K.S., Mayville, P., Pearce, J., 2022. The Greenest Solar Power? Life Cycle Assessment of Foam-Based Flexible Floatovoltaics. Sustainable Energy & Fuels, 2022, 6, 1398 - 1413. accepted version. https://doi.org/10.1039/D1SE01823J Academia OA

FPV System Design and Performance Analysis

Comparison of Electric Power Output Observed and Estimated from Floating Photovoltaic Systems: A Case Study on the Hapcheon Dam, Korea^[1]

Abstract

An interest in floating photovoltaic (PV) is growing drastically worldwide. To evaluate the feasibility of floating PV projects, an accurate estimation of electric power output (EPO) is a crucial first step. This study estimates the EPO of a floating PV system and compares it with the actual EPO observed at the Hapcheon Dam, Korea. Typical meteorological year data and system design parameters were entered into System Advisor Model (SAM) software to estimate the hourly and monthly EPOs. The monthly estimated EPOs were lower than the monthly observed EPOs. This result is ascribed to the cooling effect of the water environment on the floating PV module, which makes the floating PV efficiency higher than overland PV efficiency. Unfortunately, most commercial PV software, including the SAM, was unable to consider this effect in estimating EPO. The error results showed it was possible to estimate the monthly EPOs with an error of less than 15% (simply by simulation) and 9% (when considering the cooling effect: 110% of the estimated monthly EPOs). This indicates that the approach of using empirical results can provide more reliable estimation of EPO in the feasibility assessment stage of floating PV projects. Furthermore, it is necessary to develop simulation software dedicated to the floating PV system.

🎯 Goal

1. To compare simulated and measured EPO from a 99.36 kWp FPV system on the Hapcheon Dam.
2. To evaluate:
   • Error margins in energy prediction using SAM.
   • Adjustments needed for floating systems.
3. To support the case for dedicated FPV simulation tools.

🔍 Context

1. Floating photovoltaic (FPV) systems are expanding in Korea due to:
   • Land-use efficiency.
   • Cooling effects from water bodies increasing PV output.
   • Government support (e.g., higher REC multipliers for FPV).
2. Accurate estimation of electric power output (EPO) is critical for FPV feasibility studies.
3. Most PV simulation software, like SAM, are not calibrated for floating systems.

🚧 Research Gap

1. No commercial PV software accounts for:
   • Natural cooling effects unique to FPV.
   • Water body-specific thermal exchanges.
2. Lack of validated comparison between simulated and observed FPV performance in Korea.
3. Previous studies focused either on simulation or observation—not both combined.

🛠️ Methodology and Tools

System Description

1. Location: Hapcheon Dam, South Korea.
2. Installed: 2011; fixed-tilt system (33° tilt, south-facing).
3. Modules: 414 × 240 Wp (PVM S240 by LSIS).
4. Inverter: DSP-3350k (53 kW, Dasstech).

Simulation Approach

1. Tool: System Advisor Model (SAM) by NREL.
2. Input Data:
   • TMY weather data from Daegu (~45 km from site).
   • PV module and inverter specs.
   • Shading matrix (not used—no obstacles on site).
3. Adjustment:
   • Initial SAM simulation (without FPV cooling).
   • Additional scenario: Multiply EPO by 1.1 (110%) to simulate empirical cooling gain.

Validation

1. Compared simulation to 3-year observed hourly EPOs (2012, 2013, 2015).
2. Used RMSE, MAPE, and MBE for accuracy assessment.

📈 Results

Monthly EPOs

1. Observed annual EPO: 129,860 kWh (1307 kWh/kWp).
2. SAM-estimated annual EPO: 110,108 kWh.
3. EPO overestimated in November only; underestimated in all other months.
4. Spring yielded the highest output; summer lower due to Korea’s rainy season.

Monthly Error Metrics

1. Without correction:
   • RMSE: 1991 kWh/month
   • MBE: 1646 kWh/month
   • MAPE: ~15%
2. With 1.1 multiplier:
   • RMSE: 1329 kWh/month
   • MBE: 728 kWh/month
   • MAPE: ~9%

Hourly EPOs

1. Observed avg: 14.8 kWh/h; Estimated avg: 12.6 kWh/h
2. Max observed hourly EPO: 90.3 kWh
3. Max estimated: 78.9 kWh
4. Cooling effect more evident in high solar hours (midday, spring).

Hourly Error Metrics

1. Without correction:
   • MAPE: 75%
   • MBE: 2.4 kWh/h
2. With 1.1 multiplier:
   • MAPE: 79% (slightly worse)
   • MBE: reduced to 1.2 kWh/h

Overland vs. Floating

1. Nearby overland system: 1272 kWh/kWp/year
2. FPV system: 1547 kWh/kWp/year
3. Relative gain: +13.5% (empirical validation of cooling advantage)

💡 Discussion Highlights

1. SAM-based models underpredict FPV output due to missing thermal modeling.
2. Empirical adjustment (1.1 multiplier) improves monthly accuracy.
3. Hourly predictions more error-prone due to TMY granularity and local microclimate effects.
4. Cooling benefit is seasonal and conditional—more pronounced in spring/summer when module-water temperature gradient is large.

⚠️ Limitations

1. TMY data from a nearby city—not the dam site—affects hourly simulation accuracy.
2. Simple 10% multiplication for cooling is a coarse approximation.
3. No modeling of:
   • Wind/wave-induced module movement.
   • Real-time irradiance or albedo enhancement over water.
4. No economic or LCOE analysis included.

Design and Implementation of a Floating PV Model to Analyse the Power Generation^[2]

Abstract

The floating photovoltaic (FPV) system is a revolutionary power production technology that has gotten a lot of interest because of its many benefits. Aside from generating electricity, the technology can also prevent the evaporation of water. The electrical and mechanical structures of FPV power stations must be studied to develop them. Much research on FPV technologies has already been undertaken, and these systems have been evaluated from many perspectives. Many problems, including environmental degradation and electricity generation, fertile soils, and water management, are currently limiting societal growth. Floating photovoltaic (PV) devices save a great of land and water resources and have a greater energy conversion efficiency than standard ground power systems. A performance investigation of photovoltaic (PV) installations set on a moving platform is carried out. The paper presents and discusses various design alternatives for boosting the profitability and efficiency of floating photovoltaic (FPV) systems. Especially, FPV systems that take advantage of increasing capabilities like monitoring, conditioning, and attention were included. Although researchers have agreed on the benefits of floating systems, there has been little in-depth research on the parameters of floating photovoltaic systems. The results of this research tests were performed, and these reveal that the beneficial monitoring and conditioning impacts result in a significant gain in performance. The effects of using flat reflections on improvements are also investigated. As a result, this research examines the evolution of photovoltaic systems, then investigates the power generation capacity of floating photovoltaic systems, and then examines the benefits and possibilities of floating PV systems in depth. The concept of developing an integrated air storage system using a floating building on waters is discussed.

🎯 Goal

1. To design, implement, and analyze a floating photovoltaic power system (FPPP) that integrates:
   • Mechanical floating structure.
   • PV module support.
   • Tracking mechanisms.
   • Cooling enhancement.
2. To conduct experimental and FEM-based performance comparisons with ground-mounted PV systems.

🔍 Context

1. Floating photovoltaic (FPV) systems offer:
   • Improved efficiency due to water-based cooling.
   • Land conservation, particularly relevant in densely populated or agriculturally intensive regions.
   • Additional benefits like reduced evaporation and potential hybridization with hydropower.
2. The agricultural sector, especially in water-stressed countries, stands to benefit significantly from FPV-powered irrigation and water pumping systems.

🚧 Research Gap

1. Limited in-depth design and modeling of structural, thermal, and electrical behavior of FPV systems under real-world conditions.
2. Most FPV literature lacks:
   • Integrated simulation using finite element methods (FEM).
   • Comparative performance evaluations between FPV and land-based PV systems using field data.
   • Examination of rotational and tracking architectures tailored for floating systems.

🛠️ Methodology and Tools

System Design Components

1. Floating platform: Made of MDPE pontoons, supporting 2 PV modules each.
2. Support structure: Cold-formed metal frames for mechanical stability.
3. Articulated couplings: Allow horizontal and vertical flex under wave influence.
4. Flexible connections: Ropes or elastic materials for stress accommodation.
5. Anchors: Concrete piles transferring lateral forces to reservoir walls.
6. Underwater cabling: Waterproofed and corrosion-resistant for electrical transmission.

Thermal & Structural Modeling

1. FEM model of PV module: 5-layer polysilicon structure with front/back convective and radiative losses.
2. Use of Notton’s convective correlation and irradiance-dependent heat generation model.
3. Performance simulated under solar irradiance of 1000 W/m², ambient temperature: 32 °C (land) vs. 28 °C (water).

Experimental Configurations

1. 35 kW FPV system with cooling and flat reflectors.
2. 250 kWp FPV system with tracking.
3. Control comparison: identical-rated ground-based PV modules.

📈 Results

Performance Comparison

Parameter	Ground PV	Floating PV
Cell Efficiency (%)	15.30	15.61
Average Module Temp (°C)	32	28
Output Increase (%)	—	2.02%
Temperature Drop (°C)	—	4.5

• Performance gain primarily due to:
  • Cooling effect of water.
  • Reduced panel temperature leading to lower thermal degradation.
• Monthly data showed 3.25% gain in energy output and 0.99% gain in efficiency in floating modules vs. ground-based ones.
• Reflectors further boosted output, though with slight complexity in design.

Utility-Scale Comparisons

1. Hapcheon FPV (100 kW) vs. Haman Ground PV (1 MW):
   • FPV: 423 kWh/day → CUF: 17.5%
   • Ground PV: 3487 kWh/day → CUF (normalized): 15.6%
   • 13.5% higher utilization in FPV
2. Hapcheon FPV (500 kW) vs. Haman Ground PV (1 MW):
   • FPV: 2044 kWh/day → CUF: 17.1%
   • Ground PV: 3491 kWh/day → CUF (normalized): 15.5%
   • 10.3% higher utilization in FPV

Potential and Scalability Water surface utilization (3%) across 3000 km² could yield:

• 165 GW potential.
• 250 TWh/year energy output.
• 2×10²⁷ m³/year water saved from evaporation.
• Added indirect benefits from integrating with hydroelectric systems.

💡 Discussion Highlights

1. Floating PV is well-suited for hybrid applications with hydro or pumped storage.
2. Reflective and cooling enhancements can further increase efficiency (up to ~5–10%).
3. Rotating and tilt-tracking FPV structures show promise but add cost and mechanical complexity.
4. Structural designs need to balance:
   • Buoyancy.
   • Stability under wind and wave loads.
   • Material corrosion in saline or brackish environments.

⚠️ Limitations

1. Only a few months of data captured; longer-term degradation not studied.
2. Saltwater impacts and wave-induced fatigue require further investigation.
3. Economic and LCOE analysis not detailed—focus is technical and performance-based.

Advancing simulation tools specific to floating solar photovoltaic systems – Comparative analysis of field-measured and simulated energy performance^[3]

Abstract

The land-use intensity and performance-related issues in the solar energy sector have led to the development of floating photovoltaic (FPV) systems that allow solar photovoltaic (PV) installation on water bodies. The FPV systems present two-fold benefits in terms of mitigation of land-use conflicts and improved energy performances. While such experimental studies exist in the literature, the critical apprehensions related to performance feasibility assessments during the project planning are still unclear due to the lack of simulation tools specific to the FPV. Also, given the high uncertainty in solar PV performance, which varies from location to location, the existing experimental studies may not help in benchmarking and revealing the need for simulations specific to FPV. In reality, most installers/researchers are still using simulation tools that apply to conventional PV installations, and that do not account for the PV-water interaction and cooling effect caused. Until now, without realising this, the service providers are providing inaccurate performance feasibility reports to clients who wish to deploy FPV. Hence, this study investigates whether the existing simulation tools can be applied for FPV planning by taking a 2 MWp FPV power plant installed on the urban water reservoir in Southern India as a case study. First, the field measured data of the 2 MWp FPV plant is monitored. Second, the same is simulated in three different software tools: PVsyst, System Advisory Model (SAM) by National Renewable Energy Laboratory (NREL), and Helioscope. Third, error metrics-based methodology is applied to understand the deviation in energy output, capacity utilization factor (CUF), and performance ratio (PR). The results advocate that deviation in energy from the measured to simulated varies significantly from 18.43 to 38.55%, suggesting that none of the considered simulation tools suitable for FPV project planning. Similarly, other performance indicators are analysed, followed by a discussion and data-driven recommendations leading to the conceptual simulation tool development for FPV.

🎯 Goal

1. To assess the suitability of conventional PV simulation tools—PVsyst, SAM (NREL), and Helioscope—for FPV systems.
2. To compare simulated vs. measured performance using:
   • Daily and specific energy outputs.
   • Capacity Utilization Factor (CUF).
   • Performance Ratio (PR).
3. To provide data-driven recommendations for developing FPV-specific simulation tools.

🔍 Context

1. Floating photovoltaic (FPV) systems address:
   • Land-use conflicts common with ground-mounted PV.
   • Performance gains from water-induced cooling.
2. Despite growing installations, simulation tools used during feasibility and design stages are adapted from ground PV—not tailored for FPV.
3. Service providers often deliver inaccurate performance estimates due to the use of inappropriate models.

🚧 Research Gap

1. Lack of simulation tools that account for:
   • Water–module thermal interactions.
   • FPV-specific heat loss mechanisms.
   • Microclimate influences like humidity, wind shear, and radiation reflection over water.
2. No tool benchmarks exist using real-world FPV performance data from tropical regions.

🛠️ Methodology and Tools

Case Study System

1. 2 MWp FPV plant on Mudasarlova Reservoir, Visakhapatnam, India.
2. 6250 crystalline silicon dual-glass modules (16° tilt, south-facing).
3. Data collected over 12 months (2019) with SCADA-linked meteorological station.

Simulation Tools

1. PVsyst: Widely used in industry.
2. SAM (NREL): Modular performance analysis platform.
3. Helioscope: CAD-based layout tool popular for rapid system design.

Performance Metrics

1. Daily & specific energy outputs (kWh).
2. CUF: Ratio of actual energy to maximum possible energy at STC.
3. PR: Accounts for irradiance, temperature, and system inefficiencies.
4. Validation: MAE, RMSE, MBE, R² used for simulation–measurement comparison.

📈 Results

Solar Radiation & Temperature

1. Simulated irradiance values consistently overestimated field measurements.
2. SAM, PVsyst, and Helioscope over-predicted irradiance by up to 1 kWh/m²/day.
3. Simulated ambient temperature lower than field-measured by ~3–4°C annually.

Energy Output & Efficiency

Indicator	Measured	PVsyst	SAM	Helioscope
Annual Energy (MWh)	2577.8	2957.1	2725.6	3040.4
Specific Energy (kWh/kWp)	130.95	150.9	129.5	151.7
CUF (%)	14.74	16.90	15.75	17.37
PR (%)	79.42	75.69	71.72	77.11

Error Metrics

Tool	Energy MAE (%)	PR MBE (%)	CUF RMSE (%)
PVsyst	33.09	−3.73	2.70
SAM	18.34	−7.70	1.60
Helioscope	38.55	−2.31	2.90

• All three tools overestimated energy and CUF, and underestimated PR.
• Correlation with real performance was lower (R² ~0.71–0.78) vs. actual data (R² = 0.95).

💡 Discussion Highlights

1. Discrepancies stem from:
   • Inaccurate temperature models not accounting for water–air heat exchange.
   • Absence of FPV-specific thermal modules in existing tools.
   • Site-specific climatic parameters not properly reflected in embedded weather data.
2. Cooling effects and hydrodynamic influences require thermal and fluid-dynamic integration.

⚠️ Limitations

1. Single location and year of operation—results may not generalize.
2. Software parameter tuning was limited to available user options; deeper calibration was not possible.
3. Study does not assess economic or environmental impacts despite simulation differences.

Recommendations for FPV Simulation Tools

1. Embed thermal models specific to water body type (river/lake/sea).
2. Allow users to select installation medium and cooling models: E.g., Model 1 (for inland water): ${\displaystyle Tm=2.0458+0.9458Ta+0.0215G-1.2376Vw}$
3. Incorporate FPV-specific mounting and mooring designs.
4. Visual interface suggestion includes:
   • Location selection.
   • Weather data upload (NASA/NREL integration).
   • PV/inverter selection.
   • Energy and data visualization.
   • Exportable reports.

Authors did not use recorded weather data as input into the simulation software, instead the used simulated weather data. This could cause major errors in the comparison. Studies should simulate using both generated weather data and field-collected data if available.

Floating photovoltaic module temperature estimation: Modeling and comparison^[4]

Abstract

As the power demand increases, photovoltaic (PV) energy evolves with time, and besides the traditional ground-mounted and roof-based PV systems, floating photovoltaic (FPV) systems have gained popularity due to higher efficiency from lower module temperatures and water evaporation reductions. This paper estimates and compares the temperature of the floating PV module using thermal, empirical, and computational fluid dynamics (CFD) models. The dynamic thermal model considers a three-level energy-balance equation for the FPV module. From that, a simplified thermal model has been developed, which requires fewer parameters and is easier to estimate the module temperature. Secondly, the least squares regression was used to generate the empirical model, resulting in the smallest possible root mean square error when comparing the observed and predicted values. Finally, the FPV system has been developed in the COMSOL environment for CFD analysis using the same heat transfer method. The estimated results from the models were compared with the actual data collected from a Brazilian site and the existing FPV and ground-mounted temperature models. The RMSE performance of the FPV models was comparable to that of the data obtained from an installed FPV system and performed much better than other similar FPV models and their ground-based counterparts.

🎯 Goal

1. To develop, compare, and validate four FPV temperature models:
   • Dynamic three-layer thermal model.
   • Simplified thermal model.
   • Empirical regression model.
   • CFD model (COMSOL Multiphysics).
2. To benchmark them against actual data from a real FPV system in Brazil and existing models (e.g., Kamuyu, Niyaz, Sandia).

🔍 Context

1. FPV systems offer enhanced performance due to reduced module temperature from water cooling.
2. Accurate prediction of module temperature is critical because efficiency decreases by ~0.4–0.5% per °C increase.
3. Understanding FPV thermal behavior is essential for modeling performance, particularly in tropical climates like Brazil.

🚧 Research Gap

1. Existing models for ground-based PV modules do not translate well to FPV systems.
2. Previous FPV models either:
   • Use oversimplified empirical relations.
   • Ignore microclimate effects (humidity, wind, water temperature).
   • Lack validation against field data.

🛠️ Methodology and Tools

Modeling Approaches

1. Dynamic thermal model:
   • Three layers: front surface, PV cell, back surface.
   • Includes conduction, convection, radiation, and Joule heating.
   • Inputs: solar irradiance, wind, ambient/water/sky temperature.
2. Simplified model:
   • Aggregates heat transfers across the whole module.
   • Suitable for fast simulations with fewer parameters.
3. Empirical model:
   • Linear regression using site data: ${\displaystyle T_m=f(T_{amb},RH,G_{POA},T_w,V_w,V_{\theta },G_{GHI})}$
4. CFD model (COMSOL):
   • 3D geometry of PV module.
   • Simulates heat transfer and wind flow.
   • Uses FEM to solve for module temperature over time.

Validation Site

1. Location: Passauna Lake, Curitiba, Brazil.
2. System: 130 kWp FPV over 1200 m² water surface.
3. Duration: 2020–2022 (multi-seasonal data).
4. Data: Module temp, ambient, water temp, wind, irradiance, humidity.

📈 Results

Model Accuracy (RMSE)

1. Thermal model: 2.04 °C
2. Simplified thermal: 2.89 °C
3. Empirical model: 2.27 °C
4. CFD model: 3.26 °C
5. All outperform Kamuyu (4.49 °C) and Niyaz (3.83 °C) FPV models.

Key Observations

1. Thermal and CFD models better at capturing transient behavior (e.g., diurnal swings).
2. Simplified and empirical models easier to implement.
3. Wind speed and solar irradiance are dominant drivers of module temperature.
4. CFD shows temperature profiles and convective patterns beneath the module.

Efficiency Impacts

1. Electrical efficiency for the thermal model: 17.05%
2. Efficiency gain over Sandia ground model: up to 3%
3. Observed lower module temps in 2020; performance degraded slightly in 2021–22 (likely due to regional drought and higher water temps).

💡 Discussion Highlights

1. Water cooling effectiveness depends on:
   • Wind speed at module height.
   • Water temperature.
   • Panel tilt and placement.
2. FPV systems do not always guarantee lower module temperatures, contradicting some prior claims.
3. Microclimate modeling (humidity, wind direction) improves predictive accuracy.
4. CFD allows exploration of design changes (e.g., float geometry, airflow optimization).

⚠️ Limitations

1. CFD model is computationally intensive (6.5 min per simulation day).
2. Site-specific results—Brazilian tropical climate with low wind and high humidity.
3. Does not model soiling or shading.
4. No modeling of degradation or partial shading impacts.

Evaluation of the electrical parameters and performance of floating PV generators^[5]

Abstract

This study provides evaluation of floating photovoltaics (PV) in the Brazil tropical climate and discusses the specific technical and environmental benefits and limitations. This paper develops a model simulating the annual performance of the photovoltaic generator of a floating photovoltaic plant as a function of a given conditions. The reference is a 1.2-MWp floating-PV system commissioned in 2023 near the city of Grão Mogol, Brazil, in the reservoir of the PCH Santa Marta hydropower plant. The influence of the ambient meteorological and marine parameters on the PV module temperature, current, voltage, and power were evaluated. The simulation uses a reference crystalline-Si PV module and the Engineering Equation Solver (EES). Relevant experimental data, including incident solar radiation, ambient temperature, and wind speed were used as input data for the model. The effect of these parameters on the thermal end electrical parameters was assessed. Although small variations were found throughout the year, significant hourly and daily variations were observed, depending on solar irradiation and ambient and resulting module surface temperatures. The voltage at the maximum power decreases with the increase of the solar module surface temperature. The convective heat transfer rates are higher than the radiative heat transfer rates. This study provides a first-time complete energy and exergy analysis of a floating PV system (FPVS) incorporating the various heat transfer rates, electrical and irradiance parameters, under climate and meteorological conditions for this Brazil location.

🎯 Goal

1. To develop and validate a mathematical model for evaluating the thermal and electrical behavior of a real FPVS located in Grão Mogol, Brazil.
2. To assess the system’s:
   • Energy and exergy efficiency.
   • Module temperature variation.
   • Impact of meteorological factors.
3. To demonstrate how such a model can be generalized for other tropical locations.

🔍 Context

1. Floating photovoltaic systems (FPVS) offer benefits over land-based PV, especially in countries with abundant water surfaces like Brazil.
2. Key advantages include:
   • Reduced panel temperature from water cooling.
   • Potential for hybridization with hydropower (shared infrastructure).
   • Suppression of water evaporation and algal growth.
3. Despite global FPV growth (~3 GWp in 2022), many performance aspects remain under-characterized, especially under tropical conditions.

🚧 Research Gap

1. Lack of comprehensive energy and exergy analyses for FPVS across different seasons and climatic variations.
2. Limited empirical modeling of:
   • Heat transfer through both top and bottom module surfaces.
   • The impact of meteorological parameters (solar radiation, wind, temperature) on electrical outputs.
3. Most previous studies neglect full thermal modeling or combine exergy only with thermal losses, not electrical output.

🛠️ Methodology and Tools

System Overview

1. 1.2 MWp FPVS (Veredas Sol e Lares) with 3050 crystalline silicon modules on a hydropower reservoir (11,000 m² surface area).
2. Supplies electricity to ~1,250 families in 21 cities.

Modeling Framework

1. Inputs: Hourly data of solar radiation (global, beam, diffuse), ambient temperature, and wind speed.
2. Thermal Model:
   • Includes both convection and radiation on top and bottom module surfaces.
   • Convective heat transfer modeled using mixed (natural + forced) Nusselt number correlations.
   • Sky temperature modeled with empirical function: ${\displaystyle T_{sky}=0.0552\times T_a^{1.5}}$
3. Electrical Model:
   • Based on standard PV equations for current and voltage.
   • Open-circuit voltage and short-circuit current functions of irradiance and module temperature.
4. Energy Efficiency:
   • ${\displaystyle \eta =\frac{V_{oc}\cdot I_{sc}}{G_{T}A}}$
5. Exergy Efficiency:
   • Full derivation includes convective and radiative heat losses from both surfaces.
   • Expressed as: ${\displaystyle \psi =\frac{V_m{I}_m-{\dot{E}}_{xt}}{(1-T_a/T_{sun})G_{T}A\cdot FF}}$

📈 Results

Daily (Spring Equinox)

1. Max solar radiation: 987 W/m²
2. Max ambient temperature: 27.8 °C; Max wind: 3.9 m/s
3. Max module temperature: 48.7 °C
4. Power output peaked at 63.3 W per module.
5. Energy efficiency varied diurnally, inversely related to power generation due to temperature rise.

Annual (Monthly Averages)

1. Max monthly ambient temperature: 25.7 °C (Dec–Mar); Avg wind speed: 2.1–3.4 m/s.
2. Max module temperature: 39.7 °C
3. Voltage at maximum power point declines with module temperature.
4. Convective heat flux higher than radiative heat flux for both top and bottom surfaces:
   • Avg convective: 138 W/m²
   • Avg radiative: 115 W/m²
5. Energy efficiency remained relatively stable:
   • Max: 11.7% (July)
6. Exergy efficiency followed inverse solar radiation trend:
   • Max: 7.5% (October)

💡 Discussion Highlights

1. Thermal effects dominate electrical behavior, especially in tropical climates.
2. Convective cooling is the primary heat loss mechanism—enhanced by wind and panel-water proximity.
3. Energy efficiency is relatively insensitive to seasonal variation, but exergy efficiency varies significantly due to internal irreversibilities and ambient vs. module temperature differential.
4. Exergy analysis provides deeper insight into the thermodynamic performance and sustainability of FPVS.

⚠️ Limitations

1. Location-specific model; extension to other climates requires new input data.
2. Structural stress, soiling, and shading effects not considered.
3. Model does not account for energy storage or system degradation over time.

Innovative floating bifacial photovoltaic solutions for inland water areas^[6]

Abstract

Photovoltaic (PV) technology has the potential to be integrated on many surfaces in various environments, even on water. Modeling, design, and realization of a floating PV system have more challenges than conventional rooftop or freestanding PV system. In this work, we introduce two innovative concepts for floating bifacial PV systems, describing their modeling, design, and performance monitoring. The developed concepts are retractable and enable maximum energy production through tracking the Sun. Various floating PV systems (monofacial, bifacial with and without reflectors) with different tilts and tracking capabilities are installed on a Dutch pond and are being monitored. Results of the thermal study showed that partially soaking the frame of PV modules into water does not bring a considerable additional yield (+0.17%) and revealed that floating PV modules experience higher temperature special variance compared with land-based systems. Observations showed that the birds' presence has a severe effect on floating PV performance in the short term. Electrical yield investigation concluded that due to low albedo of inland water areas ( 6.5%), bifacial PV systems must have reflectors. One-year monitoring showed that a bifacial PV system with reflector and horizontal tracking delivers 17.3% more specific yield (up to 29% in a clear-sky month) compared with a monofacial PV system installed on land. Ecological monitoring showed no discernable impacts on the water quality in weekly samplings but did show significant impacts on the aquatic plant biomass and periods of low oxygen concentrations.

🎯 Goal

To develop, model, install, and monitor two novel floating bifacial PV system designs tailored for inland waters

• A retractable system with foldable PV arrays.
• A tumbling island system with horizontal sun tracking using ballast adjustment.

🔍 Context

• Rising global demand for clean energy + limited land availability have increased interest in alternative PV installation sites.
• Floating PV (FPV) systems offer land-saving opportunities, particularly on inland water bodies.
• Bifacial PV modules can harness both direct and reflected light, potentially increasing energy yield.
• Combining bifacial and floating PV is promising but underexplored, with limited field data and understanding of long-term ecological impacts.

🚧 Research Gap

1. Lack of field-tested, innovative FPV designs that:
   • Support bifacial modules effectively.
   • Incorporate sun tracking and reflection enhancement.
   • Account for real-world ecological effects on aquatic environments.
2. Insufficient data on actual performance and environmental consequences of FPV systems, especially on inland waters with low albedo.

🛠️ Methodology and Tools

1. Site Selection: Stormwater retention pond in Weurt, Netherlands.
2. Modeling Tools:
   • Meteonorm: Solar irradiance and SVF modeling.
   • COMSOL Multiphysics: Thermal simulations for partial module submersion.
   • PVMD toolbox: Bifacial irradiance and performance modeling.
3. Albedo and Spectral Irradiance: Measured using Kipp&Zonen albedometer and Avantes spectrometer.
4. Design and Prototyping:
   • Reflectors with 68.5% albedo (orange-coated aluminum).
   • Nine pilot systems including ground-based, fixed, tracking, and bifacial configurations.
5. Monitoring Systems: Weather sensors, irradiance meters (including rear-side), thermal cameras, camera traps, and oxygen/temperature/water quality sensors.

📈 Results

1. Albedo of water found to be very low (~6.5–8.3%), necessitating reflectors for bifacial systems.
2. Partial water soaking offered negligible performance gain (~0.17%).
3. Sun tracking with floating ballast (tumbling system) achieved:
   • <0.5% energy use for tracking.
   • 17.3% higher yield vs land-based monofacial PV.
   • Up to 29% gain in clear sky months.
4. Bird presence significantly impacted performance: Reduced reflector albedo from 68% → 24% in 8 months.
5. Thermal imaging showed: Greater temperature variance in floating modules, especially when soiled.
6. Ecological findings:
   • Water quality: No major changes in TN, TP, chlorophyll-a.
   • Plant biomass: 3× reduction under FPV panels.
   • Dissolved oxygen: Increased hypoxic periods (<6 mg/L) under FPV but no increase in anoxia (<1 mg/L).

💡 Discussion Highlights

1. Combining horizontal tracking with reflectors is a viable path to enhance FPV performance on inland waters.
2. Design positioning (height, tilt) and biofouling mitigation are critical for real-world effectiveness.
3. Ecological impacts, while manageable, need to be carefully monitored in long-term deployments.
4. The tracking system energy cost is minimal and justified by performance gains.

⚠️ Limitations

1. Short-term ecological monitoring: longer-term impacts on aquatic life cycles and nutrient cycles remain uncertain.
2. Biofouling is under-addressed -> needs active mitigation strategies.
3. Reflector effectiveness is easily compromised by wildlife activity.
4. Structural reliability in extreme weather (though tested in storms) needs further scaling validation.

Design and Control Strategy of an Integrated Floating Photovoltaic Energy Storage System^[7]

Abstract

Floating photovoltaic (FPV) power generation technology has gained widespread attention due to its advantages, which include the lack of the need to occupy land resources, low risk of power limitations, high power generation efficiency, reduced water evaporation, and the conservation of water resources. However, FPV systems also face challenges, such as a significant impact from aquatic environments on the system’s stability and safety and high operational and maintenance costs, leading to large fluctuations in the grid-connected power output. Therefore, it is necessary to integrate energy storage devices with FPV systems to form an integrated floating photovoltaic energy storage system that facilitates the secure supply of power. This study investigates the theoretical and practical issues of integrated floating photovoltaic energy storage systems. A novel integrated floating photovoltaic energy storage system was designed with a photovoltaic power generation capacity of 14 kW and an energy storage capacity of 18.8 kW/100 kWh. The control methods for photovoltaic cells and energy storage batteries were analyzed. The coordinated control of photovoltaic cells was achieved through MPPT control and improved droop control, while the coordinated control of energy storage batteries involved a droop charge–discharge mode, a constant-voltage charging mode, and a standby mode. The simulations were realized in MATLAB/Simulink and the results validated the effectiveness of the coordinated control strategy proposed in this study. The strategy achieved operational stability and efficiency of the integrated photovoltaic energy storage system.

🎯 Goal

1. To design a modular, integrated floating photovoltaic (FPV) energy storage system.
2. To develop and test coordinated control strategies for both PV and energy storage units.
3. To ensure stable operation in aquatic environments with dynamic loads and intermittent sunlight.
4. To validate the control methods using MATLAB/Simulink simulation.

🔍 Context

1. FPV systems offer:
   • High power generation efficiency.
   • Reduced land use and water evaporation.
2. However, challenges include:
   • System instability due to aquatic dynamics.
   • Fluctuations in power output to the grid.
   • High operation and maintenance costs.
3. Integrating energy storage improves stability and load management.
4. Prior FPV designs and control strategies were either focused on land or lacked granularity in control.

🚧 Research Gap

1. Most FPV systems lack:
   • Modular integration of PV with energy storage.
   • Adaptability to fluctuating aquatic environments.
   • Coordinated control strategies addressing both PV and battery systems.
2. Control strategies for land-based systems don't account for aquatic dynamics or marine load behavior.

🛠️ Methodology and Tools

System Architecture

1. Modular platform: 4 triangular floats (8 m sides) forming a 17 m square.
   • Stainless steel and foam structure ensures buoyancy and durability.
   • Middle layer: energy storage tanks and control unit.
   • Top layer: PV modules.

Electrical Design

1. Each float includes:
   • One PV array and one battery (connected to DC bus).
   • DC/DC bidirectional converters manage charge/discharge.
   • External charging interface supports peer/shore connections.

Control Strategy

1. PV system:
   • MPPT controller (perturb & observe method).
   • Constant-voltage droop control with feedforward voltage compensation.
2. Battery system:
   • SOC balancing using adaptive virtual resistance.
   • Four operating modes: droop charge, droop discharge, constant-voltage charge, standby.
3. Overall system:
   • 20 defined operational modes based on irradiance, SOC, DC bus voltage, and load status.
4. Tools: MATLAB/Simulink used to simulate and validate control performance.

📈 Results

Structural Design

1. Effective area: ~112 m² with space for PV and batteries.
2. Foam-core floats and modular hinge-connected frames provide:
   • Stability in wave conditions.
   • Safety against hull rupture or leakage.

Control Outcomes

1. MPPT and droop controls achieved smooth power output.
2. SOC management balanced charging currents among units.
3. Coordinated mode switching reduced overcharging and voltage fluctuations.
4. 20-mode control table effectively handled various operating scenarios.

Simulation Results

1. Validated system response to sudden irradiance changes and load demands.
2. Demonstrated voltage stability and efficient power delivery.
3. Showed improved control precision with feedforward compensation.

💡 Discussion Highlights

1. Modular design improves scalability and maintenance.
2. MPPT and droop control combination allows fine-grained power regulation.
3. Feedforward compensation significantly enhances DC bus voltage stability.
4. System can support islanded operations (e.g., marine platforms, isolated loads).
5. Coordination logic prevents frequent mode switching via hysteresis control.

⚠️ Limitations

1. System not tested in real-world aquatic deployment—simulation only.
2. Assumes ideal environmental sensing and communication.
3. No economic or LCOE analysis provided.
4. Long-term durability of foam-core floats not assessed under marine biofouling.

Development of compliant modular floating photovoltaic farm for coastal conditions^[8]

Abstract

Floating photovoltaic (PV) farms can be constructed in coastal marine conditions for the abundant ocean space compared to reservoirs. New challenges may arise when extending existing designs of reservoir floating PV farms to coastal regions because of the complex environmental conditions, especially for the pontoon type floating PV systems. This study presents the methodologies for the design and verification of such floating PV farms based on the practical example of one of the world's largest nearshore floating photovoltaic farms off Woodlands in Singapore. This 5 MW pilot project aims to move floating PV farms from inland water to nearshore regions for future larger-scale deployments. The innovative floating system is adapted from the successful modular floating PV development at Tengeh Reservoir and improved to withstand harsher marine environmental conditions. This study comprehensively introduces various aspects of the development of the nearshore floating modular PV farm, including its design, verification via full-scale experimental testing and numerical studies, construction, and power generation performances. The floating PV system comprises standardized floating modules made of high-density polyethylene (HDPE) that support PV panels or operational and maintenance work. A compliant design allows the floating system to follow wave motion. A verification study was conducted through full-scale experimental tests and numerical simulations based on a representative subsystem of the floating PV farm, focusing on its hydrodynamic performance. Finally, this study presents and discuss the on-site operational energy production performance. This study may serve as a reference for developing large-scale floating PV farms in coastal marine conditions.

🎯 Goal

1. To present a complete framework for the design, verification, and performance evaluation of large-scale FPV farms in coastal environments, demonstrated via a 5 MW pilot project in Singapore.
2. To verify system safety and power performance through model tests, numerical simulations, and real-world data.

🔍 Context

1. Rapid urbanization in land-scarce regions like Singapore limits land availability for ground-mounted PV systems.
2. Inland floating PV (FPV) systems have matured, but marine deployments are rare due to harsher environmental conditions (wind, waves, currents).
3. Coastal nearshore areas, which offer sheltered conditions, are attractive candidates for FPV expansion.

🚧 Research Gap

1. Lack of verified design methodologies and control strategies tailored for coastal FPV systems.
2. Absence of detailed hydrodynamic assessments, experimental validations, and long-term performance monitoring for marine FPV farms.
3. No standardized modeling frameworks to account for multibody interactions, ship wakes, and tidal variations in FPV farm design.

🛠️ Methodology and Tools

System Design

1. Modular pontoon-type system based on HDPE floating modules enhanced with:
   • Marine-adapted mooring system (buoyancy compensation to manage tidal variation).
   • Standardized connectors (nylon pins to reduce corrosion).
   • Walkway modules for O&M access.

Design Verification Framework

1. Global and local structural considerations: Station-keeping, tilt angle optimization, wave exposure.
2. Environmental Analysis:
   • Site-specific wind/wave/current from DHI modeling.
   • Ship wake estimates using empirical formulations.
3. Experimental Validation:
   • Full-scale model tests (10-module subsystem) in wave basin.
   • Captured heave and pitch motions, especially for outermost modules.
4. Numerical Simulations:
   • Time-domain potential flow (NEMOH + WEC-Sim).
   • Included multibody hydrodynamics and mooring stiffness.
   • Simulated extreme conditions with and without ship wakes.

Power Generation Evaluation

1. Compared PVWatts (pre-installation) and NASA-POWER-based (post-installation) energy yield estimates with real monitored data.
2. Performance metrics: Capacity factor, monthly energy output, and performance ratio.

📈 Results

1. Hydrodynamic Behavior
   • Outer modules exhibit highest pitch and heave under wave action.
   • Mooring lines reduced motion amplitude but increased connector forces.
   • Ship wakes caused significant dynamic responses and must be considered in coastal FPV design.
2. Power Performance
   • Average monthly generation: ~524 MWh (supports ~1,875 households).
   • Capacity factor: ~15.2% (within regional norms).
   • Post-installation prediction accuracy: 2% deviation vs measured data (vs 14% for pre-installation).

💡 Discussion Highlights

1. Modular compliant designs are effective for wave motion adaptation and O&M.
2. Ship wakes are a critical design factor in coastal zones.
3. Performance models must integrate real weather and wave-induced motion data for higher accuracy.
4. Buoyancy compensation and mooring flexibility are key in handling tides and dynamic loads.
5. Nearshore FPV designs must balance motion reduction with structural stress on connectors.

⚠️ Limitations

1. No aerodynamic load modeling—assumed negligible in benign wind environments (e.g., Singapore).
2. No structural monitoring sensors deployed yet for long-term motion tracking.
3. Wave-motion influence on power generation was not accounted for, though acknowledged.
4. Site-specific models may not generalize without local adjustments (e.g., stronger wave zones).

Challenges and opportunities towards the development of floating photovoltaic systems^[9]

Abstract

Floating solar photovoltaic (FPV) system is seen as an emerging megawatt-scale deployment option. The sustainable growth and management of FPV systems require detailed study of designs and construction, PV technologies and their performance reliability, performance modeling and cooling techniques, evaporation, economic and environmental aspects of these systems. The specific design and structure of the FPV influence its output power generation, durability and investment cost; thus, the overview of various design and construction strategies along with the offshore PV technology and current status of FPV systems have been presented in this paper. Various new PV technological modules are rapidly evolving these days; therefore, PV technologies for FPV systems have been discussed. The performance and reliability of FPV from the electrical point of view under the harsh environment of water bodies is a major challenge for their cost-effective power generation. Detailed analysis and updated review on the performance and degradation aspects of PV systems under the water bodies’ climate have been presented. To meet the desired energy demand and secure investment in PV systems, prior prediction of PV systems' performance at a particular location is necessary. Thus, this study attempts to model the performance and temperature of PV modules on water bodies. Also, the active cooling techniques and evaporation rate in FPV systems have been discussed. Furthermore, the economic evaluation and environmental impacts of FPV systems are essential for their rapid expansion and investment perspective. Therefore, the economic feasibility and environmental effects of floating PV systems have been explored in this paper.

🎯 Goal

1. Present a state-of-the-art review of FPV systems covering:
   • Structural designs.
   • PV technology integration.
   • Performance modeling and degradation.
   • Cooling and evaporation dynamics.
   • Economic analysis and environmental impact.
2. To highlight key challenges and research opportunities for FPV growth and standardization.

🔍 Context

1. Floating photovoltaic (FPV) systems present a promising alternative to land-based PV, especially for:
   • Land-scarce regions.
   • Enhancing water-use efficiency via evaporation reduction.
2. FPV offers potential benefits including better cooling, reduced dust, and hybridization with hydropower plants.
3. Despite rapid deployment, technical, economic, and environmental uncertainties persist.

🚧 Research Gap

1. Absence of comprehensive synthesis integrating:
   • FPV structural and system design types.
   • PV technologies suited to aquatic conditions.
   • Performance and degradation behavior in high-humidity environments.
   • Temperature and performance modeling tailored to FPV.
   • Quantified cooling and evaporation benefits.
   • Economic and environmental risk assessments.
2. Lack of consolidated standards for FPV structural design, especially for offshore and tracking systems.

🛠️ Methodology and Tools

1. Review paper combining:
   • Published literature.
   • Global case studies and pilot projects.
   • Technological trends (materials, tracking, cooling).
   • Simulation outcomes (e.g., exergy analyses, irradiance modeling).
2. Categorizes FPV structures into three main types:
   • HDPE pipes + metal raft (Type 1)
   • Fully HDPE-based modular floats (Type 2)
   • Marine platform-style pontoons (Type 3)

📈 Results

Technology and Design

1. HDPE is the dominant material due to buoyancy, corrosion resistance, and low cost.
2. Innovative layouts (e.g., Honeycomb floats, retractable/foldable PV islands, submerged modules) enable custom adaptation.
3. Tracking mechanisms on water are viable but costly and mechanically complex.

PV Technology Integration

1. Crystalline silicon (c-Si) remains dominant, but:
   • Thin-film, bifacial, and HIT modules gaining popularity.
   • Dye-sensitized solar cells offer transparency and flexibility for ecological applications.

Performance and Degradation

1. Cooling from water improves module performance, but:
   • Humidity-induced degradation is a concern.
   • Exergy analysis shows submerged PV performs best thermally, followed by FPV and ground PV.

Modeling and Optimization

1. Optimum tilt, height, and pitch critical for bifacial FPV yield.
2. Water’s low albedo (~7–8%) limits bifacial gains unless reflectors are used.
3. Models accounting for wave motion improve tilt angle predictions and energy yield forecasts.

Economic & Environmental Aspects

1. Hybrid hydro-FPV systems lower LCOE and increase capacity factors (~17% gain).
2. Evaporation savings and CO₂ reduction add to environmental value.
3. Risks include:
   • Visual and ecological impact.
   • Wave and wind stress, especially offshore.
   • Lack of policy support and grid-integration standards.

💡 Discussion Highlights

1. FPV is viable for megawatt-scale deployment, especially over man-made reservoirs.
2. Global potential >400 GW on only 1% of reservoir surfaces.
3. Combining bifacial PV and FPV can increase output, but requires structural trade-offs.
4. Most performance improvements rely on location-specific optimization and new structural designs.

⚠️ Limitations

1. Mostly secondary data and simulation-based insights.
2. Lacks real-world long-term monitoring of structural durability and ecosystem impact.
3. Many proposed systems (e.g., submerged PV, tracking FPV) are conceptual or lab-scale.
4. Regulatory frameworks and standardization are still evolving.

Reviewing floating photovoltaic (FPV) technology for solar energy generation^[10]

Abstract

Energy scarcity in various regions worldwide not only adversely affects people's quality of life but also hinders overall development. Pakistan is among the nations grappling with energy shortages, with high consumption and limited generation, resulting in a substantial energy shortfall of 2500 MW. Floating photovoltaic (FPV) systems present an attractive solution for harnessing solar energy, particularly where land availability is constrained. These systems offer benefits such as conserving water and land while delivering higher power output compared to conventional terrestrial PV systems. While the advantages of FPV systems are generally recognized, research on their specific characteristics remains limited. This paper aims to address this gap by providing a comprehensive review of FPV technology and its potential applications, particularly in Pakistan. By comparing ground-mounted and FPV systems, the study explores the economic, technological, and environmental implications of FPV adoption in regions with similar geographical profiles. The analysis highlights not only the cooling impact of water, which enhances the efficiency of FPV systems, but also other key aspects such as cost-effectiveness, site preparation, and environmental impact. Output power of FPV and land based obtained are 390 kW and 370 kW at irradiances of 180kW/m2and 170 kW/m2 at temperature from 30 to 35°C respectively. The findings demonstrate the viability of FPV systems and emphasize that by leveraging the characteristics of water temperature, it becomes feasible to more accurately predict the electricity generation potential of FPV systems. This synthesis offers new insights and underscores the potential for FPV adoption in areas facing similar energy challenges.

🎯 Goal

To provide a comprehensive review of FPV systems covering:

1. Design elements and materials.
2. Performance benefits and cooling dynamics.
3. Economic and ecological comparisons with land-based PV.
4. Potential for large-scale deployment in Pakistan and similar regions.

🔍 Context

1. Global energy scarcity is exacerbated in developing countries like Pakistan, where a shortfall of ~2500 MW persists.
2. Floating photovoltaic (FPV) systems provide a land-saving alternative to terrestrial PV systems, offering additional benefits such as:
   • Water conservation by reducing evaporation.
   • Higher output due to passive cooling from water bodies.
3. The potential of FPV is significant, especially in regions with high solar insolation and water surface availability.

🚧 Research Gap

Despite growing interest, there is limited consolidated literature on:

1. • Comprehensive comparison of FPV vs. land-based PV performance across multiple climates.
   • Design considerations and degradation mechanisms specific to aquatic environments.
   • Environmental impacts and mitigation strategies.
   • Feasibility of FPV in developing countries, particularly in South Asia.

🛠️ Methodology and Tools

1. Extensive literature review and synthesis of:
   • Case studies from Asia, Europe, South America, and Australia.
   • Experimental results comparing FPV and ground-mounted PV systems.
   • Modeling approaches for cooling, energy gain, and evaporation.
   • National and global data on FPV deployments and theoretical potential.
2. Use of tools such as:
   • PVSYST software for energy modeling.
   • Empirical thermal and power output comparisons.

📈 Results

Technical and Performance

1. Cooling Effects:
   • Water cooling reduces PV module temperature by 3–14.5°C.
   • FPV systems with direct water contact outperform air-cooled FPV systems by 5–7%.
   • Performance improvement of 3–12% compared to ground-mounted PV.
2. Evaporation Reduction: Covering just 30% of a basin can reduce evaporation by 50%.
3. Materials: HDPE dominates due to UV/corrosion resistance, buoyancy, and recyclability.
4. Design Optimization:
   • Tilt angles and spacing affect both yield and albedo reception.
   • Wave motion introduces tilt instability, requiring robust mooring and design.

Global and Regional Potential

1. Pakistan, India, Bangladesh, and Nepal are promising due to large water body networks and high solar exposure.
2. If 1% of global man-made reservoirs were used, 5211 TWh/year of energy could be generated.
3. Example: Brazil could produce 12% of its power demand using just 1% of its artificial water bodies.

Economic Considerations

1. FPV has higher CAPEX, but:
   • Benefits from reduced land acquisition.
   • Improves yield, especially in hybrid hydro-FPV systems.
2. Power densities and tracking potential are higher on water due to fewer shading constraints.

💡 Discussion Highlights

1. FPV systems demonstrate consistent energy gains due to better thermal regulation.
2. Environmental benefits include:
   • Reduced algal growth.
   • Potential for hybrid hydro-electric integration.
3. Challenges include:
   • High humidity corrosion.
   • Wave/wind stress-induced vibrations (may cause microcracks).
   • Maintenance complexity and mooring system requirements.

⚠️ Limitations

1. Lack of long-term durability data.
2. Ecological effects on aquatic life and water quality remain insufficiently explored.
3. Design standards are not yet universal—performance depends heavily on climate, water conditions, and floatation strategy.
4. Offshore applications remain limited due to mechanical and cost challenges.

Mitigation and Future Directions

1. Mitigation Strategies:
   • Environmental Impact Assessments (EIA).
   • Thoughtful site selection with minimal ecological disruption.
   • Modular designs with minimal shading footprint.
   • Community engagement and policy support.
2. Future Work:
   • Techno-economic feasibility for Pakistan and similar countries.
   • Pilot projects for inland water bodies.
   • Grid integration strategies and storage solutions.
   • Training local workforce for deployment and maintenance.

Developing reliable floating solar systems on seas: A review^[11]

Abstract

Solar PhotoVoltaic (PV), as a clean and affordable energy solution, has become ubiquitous around the world. In order to install enough PV coverage to meet the demand of global climate action, there has been a growing research interest in deploying solar panels on abundant sea space. However, the harsh marine environment is holding stakeholders back with safety concerns. There is a necessity to ensure the reliability of FPV on seas. To facilitate research in this area, the present review scans all Floating PV (FPV) literature related to the ocean, with a focus on reliability and risk mitigation. It starts by presenting contemporary and potentially future FPV designs for seas, inventorying both mechanical and electrical components. Accordingly, possible risks in the system are discussed with the associate mitigations suggested. Subsequently, a series of protective approaches to assess offshore wind and wave loads on FPV are introduced. This is followed by a structural integrity review for the system’s fatigue and ultimate strength, accompanied by anti-corrosion, anti-biofouling, and robust mooring concerns. Finally, essential research gaps are identified, including the modelling of numerous floating bodies on seas, mooring methodology for enormous FPV coverage, the interactions between FPV and the surrounding sea environments, and remote sensing and digital twins of the system for optimal energy efficiency and structural health. Overall, this work provides comprehensive insights into essential considerations of FPV on seas, supporting sustainable developments and long-term cost reductions in this sector.

🎯 Goal

1. To provide a comprehensive review of the challenges, designs, and risk mitigation strategies for developing reliable FPV systems on seas.
2. To inform future engineering, modeling, and material innovations for scalable and robust ocean FPVs.

🔍 Context

1. Floating photovoltaic (FPV) technology is growing rapidly as a land-saving renewable energy solution.
2. While FPVs are increasingly deployed on inland waters, seas remain underutilized due to harsh environmental conditions.
3. Marine environments introduce mechanical, electrical, and operational risks that require new designs, materials, and maintenance strategies.

🚧 Research Gap

1. Lack of comprehensive studies focused specifically on FPV reliability in offshore/marine environments.
2. Gaps exist in:
   • Structural integrity under waves and wind.
   • Mooring system optimization.
   • Electrical risks (e.g., corrosion, insulation failure).
   • Wave/wind load modeling and prediction.
   • Long-term fatigue analysis and system monitoring tools.

🛠️ Methodology and Tools

1. Systematic literature review using Web of Science (547 papers).
2. Review grouped into key areas:
   • Mechanical designs and mooring systems.
   • Electrical system integration and reliability.
   • Wind and wave load modeling (analytical, CFD, hybrid).
   • Structural assessments (fatigue, corrosion, mooring life).
   • Identification of key research gaps and future directions.

📈 Results

Mechanical Design & Structures

1. Two major FPV design types:
   • Pontoon type: elevated truss-based; more robust but costly.
   • Superficial type: panels float on surface; cost-efficient but vulnerable.
2. Notable prototypes: SolarDuck, Moss Maritime, CIMC, Ocean Sun, and Oceans of Energy—each tested under extreme wave heights (up to 13m).
3. Innovations:
   • Breakwater-integrated FPV.
   • Combined Wave Energy Converters (WECs) with FPV for energy and protection.

Mooring Systems

1. Designs include:
   • Catenary and taut-leg lines.
   • Anchors: drag embedment, suction piles, gravity-based, etc.
2. Emphasis on:
   • Balancing mooring tension vs. flexibility.
   • Durability against marine growth and corrosion.
   • Software tools: OrcaFlex, AQWA, MOSES.

Electrical Systems

1. Key components: waterproof combiner boxes, DC cables, rapid shutdown systems, marine-grade inverters/transformers.
2. Challenges:
   • Salt corrosion, insulation breakdown, MC4 connector degradation.
   • Emergency systems must account for fire and overheat scenarios (>70°C).
3. Importance of underwater earthing and surge protection in lightning-prone zones.

Risk Categories

1. Mechanical risks: Structural fatigue, marine growth, excessive tilt motion.
2. Electrical risks: Corrosion, fouling (bird droppings), lightning-induced surges, component overheating.
3. Use of design safety factors (ULS, FLS, SLS, ALS) and load/material safety coefficients.

Wind & Wave Loads

1. Loads depend on panel tilt, wave synchronization, and resonance.
2. Modeling approaches:
   • Analytical (e.g., Morison equation).
   • CFD using SST k-ω turbulence models.
   • Hybrid models combining CFD with machine learning for real-time prediction.

Structural Assessment

1. Topics covered:
   • Fatigue under cyclic wave loads.
   • Biofouling and corrosion prevention.
   • Mooring wear and anchor reliability.
2. Standards: DNVGL-RP-0584, EN1990, EN1999-1-1.

💡 Discussion Highlights

1. Wave-induced motions reduce energy yield due to shifting tilt angles.
2. Biofouling and corrosion change hydrodynamic and weight properties, increasing design uncertainty.
3. Breakwater-WEC hybrid could offset structural cost while enhancing protection and power output.
4. Real-time monitoring, digital twins, and smart sensing are vital for future large-scale deployments.

⚠️ Limitations

1. Many prototypes are still at small-scale or pilot stages.
2. No long-term datasets available on system fatigue or ecological impact.
3. Cost modeling for offshore FPV is still evolving.
4. CFD studies are computationally intensive and require simplification for large-scale deployment.

Floating photovoltaics could mitigate climate change impacts on water body temperature and stratification^[12]

Abstract

Floating solar photovoltaics, or floatovoltaics (FPV), are a relatively new form of renewable energy, currently experiencing rapid growth in deployment. FPV decarbonises the energy supply while reducing land-use pressures, offers higher electricity generating efficiencies compared to ground-based systems and reduces water body evaporation. However, the effects on lake temperature and stratification of FPV both sheltering the water’s surface from the wind and limiting the solar radiation reaching the water column are unresolved, despite temperature and stratification being key drivers of the ecosystem response to FPV deployment. These unresolved impacts present a barrier to further deployment, with water body managers concerned of any deleterious effects. To overcome this knowledge gap, here the effects of FPV-induced changes in wind speed and solar radiation on lake thermal structure were modelled utilising the one-dimensional process-based MyLake model. To resolve the effect of FPV arrays of different sizes and designs, observed wind speed and solar radiation were scaled using a factorial approach from 0% to 100% in 1% intervals. The simulations returned a highly non-linear response, dependent on system design and coverage. The responses could be either positive or negative, and were often highly variable, although, most commonly, water temperatures reduce, stratification shortens and mixed depths shallow. Modifications to the thermal dynamics of the water body may subsequently drastically alter biogeochemical processes, with fundamental implications for ecosystem service provision and water treatment costs. The extreme nature of response for particular wind speed and solar radiation combinations results in impacts that could be comparable to, or more significant than, climate change. As such, depending on how they are used, FPV have the potential to mitigate some of the impacts of climate change on water bodies and could be a useful tool for water body managers in dealing with changes to water quality, or, conversely, they could induce deleterious impacts on standing water ecosystems. These simulations provide a starting point to inform the design of future systems that maximise ecosystem service and environmental co-benefits from this growing water body change of use.

🎯 Goal

1. To simulate and quantify the influence of FPV systems (at varying scales and configurations) on:
   • Water temperature profiles.
   • Stratification duration and stability.
   • Mixed layer depth.
2. To inform lake management and FPV design for maximized climate and ecosystem co-benefits.

🔍 Context

1. Floating solar photovoltaics (FPV) are growing rapidly as a land-saving renewable energy source.
2. FPV can offer climate co-benefits, such as reduced water body evaporation and enhanced energy yield due to cooling.
3. However, the impact of FPV on aquatic ecosystems, especially on water temperature and stratification, remains poorly understood.
4. Lake thermal dynamics are crucial for ecosystem processes like nutrient cycling, oxygen levels, and algal blooms.

🚧 Research Gap

1. No prior study systematically modeled the thermal impact of FPV arrays on water bodies.
2. Unknown:
   • How FPV-induced changes to wind speed and solar radiation alter thermal stratification.
   • Whether such changes are beneficial or harmful.
3. Managers of water bodies lack guidance on the environmental risks and design considerations for FPV deployment.

🛠️ Methodology and Tools

1. Model: MyLake v1.2 – a 1D process-based lake model for temperature, evaporation, and ice formation.
2. Study Site: South basin of Lake Windermere, UK (deep, monomictic, mesotrophic).
3. Data Inputs:
   • 2009 meteorological data: wind, solar radiation, temperature, humidity.
   • In-lake temperature profiles (12 depths), bathymetry, discharge data.
4. Factorial Experiment:
   • Reduced wind and solar radiation in 1% intervals (0–100%).
   • Tested 3 scenarios:
     • Equal (1:1) reduction.
     • Wind-dominant (wind 80% of solar reduction).
     • Solar-dominant (solar 80% of wind reduction).
5. Analysis Tools: Lake Analyzer for mixed layer depth, Schmidt stability.

📈 Results

Water Temperature

1. FPV systems mostly reduced surface and bottom water temperatures.
2. Reductions were non-linear; small FPV coverage had minor effects; large coverage (>50%) had large cooling.
3. Ice formation occurred in simulations with >90% radiation/wind reduction—uncommon for Windermere.

Stratification

1. Shortened duration with increasing coverage (up to 214-day reduction in extreme cases).
2. Stratification delayed in wind-dominant scenarios, but advanced in solar-dominant ones.
3. Schmidt stability generally declined except when solar reduction was minimal but wind reduction was large.

Mixed Layer Depth

1. Shallowed for most FPV scenarios (up to 50% reduction).
2. Some extreme cases led to deepening or full mixing.
3. Mixed layer depth was more sensitive to wind speed than radiation.

Evaporation

1. FPV consistently reduced evaporation.
2. At >74% coverage, dew formation exceeded evaporation → net water gain.

💡 Discussion Highlights

1. FPV can act as a climate adaptation tool by reducing warming and evaporation.
2. However, improper deployment could exacerbate hypoxia, delay mixing, or promote undesirable algae.
3. Non-linear responses mean design must be tailored per site.
4. Shifts in phytoplankton dynamics, stratification timing, and potential for ice formation must be considered.

⚠️ Limitations

1. Model is 1D—does not capture horizontal heterogeneity or circulation.
2. Only one lake studied (Windermere); results may not generalize to shallow, polymictic, or tropical lakes.
3. Ecosystem responses beyond thermal dynamics (e.g., fish, plankton) are inferred, not simulated.

Key issues in the design of floating photovoltaic structures for the marine environment^[13]

Abstract

The floating photovoltaic (FPV) market has been expanding at an impressive rate over the last decade, doubling its global installed capacity year after year. This growth was possible due to the numerous advantages FPV plants pose over ground-mounted plants, which are mainly related to land occupation and energy efficiency. However, this expansion has been limited to freshwater applications, despite the vast potential that the offshore environment entails. The lack of maturity of the sector and the harsher environmental conditions have hindered the transition of this technology to the marine environment. Furthermore, a lack of publications regarding the structural analysis of this technology was found, as well as no specific designs standards for marine FPV. On these grounds, this article reviews the design aspects of this technology with a focus on marine applications, highlighting relevant aspects to be tackled. First, the main components of the FPV technology are described and their compatibility with the marine environment is assessed. Then, a structural classification of the current plants is proposed. This allows the individual suitability analysis of each typology for the marine environment. Existing marine FPV projects are described and classified. Afterwards, synergies between marine FPV plants and other sectors are gathered and discussed. Finally, general design guidelines are provided, with a focus on the structural response of FPV structures subjected to marine environmental actions. Insight on the nature of these actions (wind, waves, currents, and tides) as well as how they interact with FPV plants is provided.

🎯 Goal

1. To analyze and classify FPV designs with respect to their suitability for marine environments.
2. To propose general design guidelines considering:
   • Structural response under marine loads.
   • Synergies with other offshore sectors.
   • Environmental and operational challenges.

🔍 Context

1. Floating PV (FPV) is expanding rapidly on inland waters due to benefits such as:
   • Land savings.
   • Cooling-induced efficiency gains.
   • Reduced shading losses.
2. However, transition to marine environments is still limited due to:
   • Harsher environmental conditions.
   • Lack of tailored structural standards and maturity.
   • New risks like saltwater corrosion, waves, and tides.

🚧 Research Gap

1. Absence of marine-specific FPV design frameworks, especially for:
   • Structural and environmental load analysis.
   • Mooring, material degradation, and dynamic response modeling.
2. No universal design standards for marine FPV systems.
3. Minimal empirical validation and pilot testing in high-energy coastal areas.

🛠️ Methodology and Tools

1. Literature review of FPV systems, materials, and offshore energy standards.
2. Classification of FPV designs into:
   • Pontoon types (Classes 1–3).
   • Superficial/flexible designs (e.g., thin-film arrays).
3. Structural analysis approaches:
   • Analytical models (e.g., Morison equation).
   • CFD, FEM, and BEM for load/response modeling.
4. Design standards referenced:
   • Eurocodes (EN series).
   • API, ASCE, ASTM, DNV.
   • Offshore wind and wave energy guidelines.

📈 Results

Structural Components and Materials

1. Floats:
   • HDPE is dominant, but may require antifouling coatings.
   • Risk of microplastic pollution—sustainable materials preferred.
2. Support Structures:
   • Metals (steel, aluminum) vulnerable to corrosion.
   • FRP recommended for durability and low density.
3. Mooring Systems:
   • Catenary, taut, compliant, and rigid systems reviewed.
   • Suction foundations and Seaflex® effective under tide and wave variability.
4. PV Modules:
   • Crystalline silicon most used; thin-film for flexibility in waves.
   • Salt, UV, and humidity cause cracking and delamination—countered via encapsulants and coatings.
5. Electrical and Storage Systems:
   • Waterproofed components necessary.
   • Innovations include Water Veil Cooling (WVC) and CAES.
   • Energy storage via hydrogen, CAES, or pumped hydro proposed.

FPV Design Typologies

1. Class 1 (pontoon with trusses): Rigid, robust, but costly; suited for moderate marine exposure.
2. Class 2 (integrated floats): Common in freshwater; low cost but unsuitable for harsh marine use without adaptation.
3. Class 3 (floating islands): Walkable, modular, high-cost; best for high-wave marine conditions.
4. Superficial/flexible FPV: Thin-film or semi-submerged arrays offer thermal and hydrodynamic benefits but lower yields.

Environmental Load Modeling

1. Wind: Primary concern for freshwater; affects PV tilt, buoyancy, mooring.
2. Waves: Most critical marine load; requires nonlinear modeling.
3. Currents: Can erode foundations and cause mooring fatigue.
4. Tides: Affects mooring length/design; linked to wave propagation and scour.

Design Methods

1. Load Modeling:
   • Analytical (Airy, Stokes, Morison) and numerical (CFD).
   • Multidirectional, irregular wavefronts advised.
2. Response Modeling:
   • Rigid body dynamics for pontoons.
   • Hydroelastic modeling for flexible systems.
   • Time-domain and frequency-domain analyses necessary for fatigue estimation.

💡 Discussion Highlights

1. Marine FPVs must prioritize survivability over cost—a reversal from freshwater FPV design.
2. FPV's synergy with offshore wind (OWT) offers:
   • Higher density.
   • Combined power smoothing.
   • Shared grid/O&M infrastructure.
3. Potential co-applications:
   • Desalination, aquaculture, ports, offshore oil/gas.
   • E.g., Ocean Sun, DNV SUNdy concepts in real-world trials.

⚠️ Limitations

1. Limited real-world deployment in fully offshore (high-wave) conditions.
2. Structural testing often omits irregular seas and long-term fatigue.
3. Mooring and anchoring systems not standardized for FPV.
4. Thin-film systems promising but less efficient and commercially immature

Floating photovoltaic plants: Performance analysis and design solutions^[14]

Abstract

The analysis of the performance of photovoltaic (PV) installations mounted on a floating platform is performed. Different design solutions for increasing the efficiency and cost effectiveness of floating photovoltaic (FPV) plants are presented and discussed. Specifically, FPV solutions that exploit the advantages of additional features such as tracking, cooling and concentration, are presented. The results of experimental tests are reported and they show a considerable increase in efficiency due to the positive tracking and cooling effects. Gains due to the use of flat reflectors are also analyzed. Finally, the possibility of exploiting the floating structure on water in order to develop an integrated air storage system is presented.

🎯 Goal

1. To evaluate and present design innovations and performance data for FPV systems that include:
   • Water veil cooling (WVC).
   • Tracking systems (especially bow-thruster-based).
   • Flat and Λ-shaped reflectors for light concentration.
   • Modular rafts with potential for compressed air energy storage (CAES).
2. To compare FPV energy yield under different configurations against land-based PV systems.

🔍 Context

1. The global expansion of PV technologies is hindered by:
   • Land use constraints.
   • Efficiency losses due to temperature.
   • Intermittency and cost of energy storage.
2. Floating PV (FPV) plants offer a novel platform that may improve energy yield while addressing land and thermal limitations.
3. FPV enables integration of tracking, cooling, light concentration, and storage—capabilities rarely exploited simultaneously in terrestrial systems.

🚧 Research Gap

1. Limited empirical studies on:
   • Real-world performance gains from tracking and cooling in FPV.
   • Integration of compressed air energy storage (CAES) with FPV.
   • Use of rear and Λ-shaped reflectors for concentrating sunlight.
2. Most FPV installations use simple fixed platforms, without utilizing additional technological enhancements.

🛠️ Methodology and Tools

1. Field-tested prototypes at two sites in Italy:
   • Pisa (30 kWp): cooling, tracking, reflectors.
   • Suvereto (200 kWp): tracking, multi-year operation.
2. Experimental setups included:
   • South-oriented fixed and tracked modules.
   • PVGIS simulation for yield prediction.
   • Thermal and optical models of submerged and floating PV modules.
   • Mechanical design simulations of platforms under wind and wave loads.
3. Innovations included:
   • Bow-thruster-controlled rotation.
   • Sun-tracking via image processing and electronic guidance systems.
   • Compressed air storage using raft tubing.

📈 Results

Structural Design

1. Modular raft designs (metal + HDPE) showed robust behavior in strong winds (up to 140 km/h).
2. Tire-based mono-pipe rafts proposed for offshore use to reduce stress and cost.

Cooling

1. Water Veil Cooling (WVC) increased energy yield by 10–15% annually.
2. Efficiency gains arise from:
   • Lower cell temperatures.
   • Reduced optical losses (refractive index advantage).
3. Energy cost for pumping water was only ~0.25% of energy produced.

Tracking

1. Bow-thruster tracking achieved <2° error with image-based solar alignment.
2. Vertical-axis tracking was suitable and economical for FPV platforms.

Light Concentration

1. Rear reflectors improved energy yield by ~18–33% (ideal case).
2. Measured gains under field conditions reached up to 1.8× (vs. 2.14 theoretical maximum).
3. Λ-shaped reflectors allowed diffuse-light utilization and lower mechanical complexity.

Energy Storage

1. Proposed CAES integrated into raft pipes with:
   • Up to 200 bar pressure.
   • Effective isothermal compression due to water thermal mass.
2. Potential for night-time energy release and grid-independent operation.

Experimental Outcomes

1. Pisa FPV showed:
   • 8–12% gain with WVC.
   • Up to 20% gain with reflectors + WVC.
2. Suvereto FPV showed:
   • 4% higher energy output than simulated fixed system.
   • Data validated vertical tracking efficiency.

💡 Discussion Highlights

1. Combining cooling, tracking, and light concentration is feasible and beneficial for FPV.
2. FPV platforms can be enhanced further through multi-functional raft design (CAES, hybrid modules).
3. Reflectors are particularly valuable in clear-sky, arid regions.
4. Performance gains depend heavily on climate, module type, and site-specific design.

⚠️ Limitations

1. Submerged PV (SP2) modules only tested in labs—not implemented in pilot plants.
2. Reflectors underperform in diffuse-light-dominant climates.
3. Economic analysis was not detailed; structural costs only qualitatively

Comprehensive review of advancements, challenges, design, and environmental impact in floating photovoltaic systems^[15]

Abstract

Floating photovoltaic (FPV) systems have emerged as an innovative and sustainable solution for renewable energy generation, offering advantages such as enhanced efficiency, land conservation, and integration with aquatic environments. This review examines critical factors influencing the efficiency, cost-effectiveness, and long-term viability of FPV systems compared to conventional land-based photovoltaic installations. Key considerations include the natural cooling effect of water, structural stability under environmental forces, electrical system optimization for safety and performance, and site selection to balance ecological preservation with energy generation. The study also explores maintenance strategies to address challenges like biofouling and corrosion, along with the environmental impacts of FPV systems on aquatic ecosystems, water quality, and biodiversity. Advanced corrosion protection methods, including multilayer coatings and cathodic protection, are highlighted for their role in extending system durability, while innovations in design, such as compliant modular structures, address stability in variable-depth and high-stress environments. FPV systems benefiting from reduced maintenance and enhanced energy output due to water's cooling effect. Case studies, such as the Huainan Coal Mine FPV system in China and the Omkareshwar Reservoir FPV project in India, demonstrate the transformative potential of FPV technology in mitigating climate change, optimizing land use, and promoting energy security. The review provides a comprehensive framework for successful FPV system deployment, offering actionable insights for engineers, policymakers, and stakeholders to advance sustainable energy solutions.

🎯 Goal

To provide a comprehensive review of:

1. FPV system design, efficiency, corrosion resistance, and maintenance.
2. Structural, electrical, and hydrodynamic considerations.
3. Environmental impacts and mitigation strategies.
4. Case studies demonstrating global deployment success and lessons.

🔍 Context

1. Floating photovoltaic (FPV) systems are gaining global attention for:
   • Saving land space.
   • Enhancing solar panel efficiency via water cooling.
   • Offering sustainable energy generation on reservoirs, lakes, and coastal regions.
2. Countries like China, India, Germany, Indonesia, and Kenya are deploying FPV for climate action and grid resilience.

🚧 Research Gap

Despite rapid growth, several issues remain underexplored:

1. Long-term durability and material degradation.
2. Corrosion protection strategies and electrical safety.
3. Standardized design frameworks for harsh marine and freshwater environments.
4. Ecological impacts on aquatic ecosystems.
5. Site selection and FPV survivability during extreme weather events.

🛠️ Methodology and Tools

1. Review of experimental studies, field deployments, and simulation-based research.
2. Multi-disciplinary approach: civil, mechanical, electrical, and environmental engineering.
3. Key aspects analyzed include:
   • Cooling performance.
   • Mooring and anchoring design.
   • Corrosion test results (e.g., EIS, SEM, Tafel).
   • GIS and MCDM for site suitability.
   • Economic performance and lifecycle assessment.

📈 Results

Efficiency and Performance

1. FPV panels are up to 12–16% more efficient than land-based PV due to natural cooling.
2. Water-integrated systems show improved capacity factors and lower LCOE in many regions.
3. Integration with hydroelectric plants boosts energy output by up to 92% and enhances capacity factor by 18.43%.

Site Selection

1. Inland water bodies (reservoirs, dams, ponds) favored for:
   • Flat surfaces.
   • Existing grid proximity.
   • Lower environmental sensitivity.
2. Offshore FPVs viable in high electricity tariff and land-scarce nations (e.g., Japan).
3. Tools: GIS, GHI maps, fuzzy AHP for multi-criteria site evaluation.

Structural Design

1. Must withstand wind, waves, and water-level fluctuations.
2. Glass-Fiber Reinforced Plastic (GFRP) preferred for offshore durability.
3. Modular platforms enhance scalability, stability, and maintenance.
4. API, ClassNK, and VTV (Vulnerability-Threat-Value) models used for survivability assessment.

Electrical System Design

1. Focus on:
   • Lifecycle cost vs. performance ratio.
   • Minimizing leakage current (<300 mA).
   • Waterproof cables, grounding, and DC voltage safety (<60V threshold).
2. Insulation and grounding essential to mitigate electric shock risk in aquatic environments.

Maintenance

1. FPV has higher O&M demands than land PV due to:
   • Biofouling.
   • Corrosion.
   • Wave-induced mechanical wear.
2. Costs can reach 5–15% of initial CAPEX annually.
3. Cleaning, damage inspection, and component replacement needed more frequently.

Environmental & Hydrodynamic Factors

1. FPV affects:
   • Light penetration.
   • Oxygen and nutrient levels.
   • Ecosystem dynamics (thermal stratification, benthic habitat disruption).
2. Wave, wind, and tidal forces dictate mooring type and spacing.
3. Extreme pitch angles (>6°) reduce yield by up to 12.7%.

Corrosion Protection

1. Key methods:
   • Coating systems: multilayer polyurethane/epoxy/zinc.
   • Cathodic protection (CP): Galvanic (zinc, Al, Mg) and ICCP (solar-powered).
   • Sacrificial anodes: protect interconnects and pontoons.
2. Corrosion-related costs can be 50% of system lifetime if unaddressed.

💡 Discussion Highlights

1. Compliant modular platforms improve survivability in variable-depth zones.
2. Risk assessment matrices and test-to-fail protocols essential before deployment.
3. Site-specific strategies required for:
   • Anchorage design.
   • Panel tilt optimization.
   • Bio-ecological compatibility.
4. FPV's potential as part of multi-use infrastructure (hydropower, aquaculture, oil platforms).

⚠️ Limitations

1. Lack of long-term empirical data from marine FPVs.
2. Limited field tests validating corrosion and fatigue under variable environments.
3. Unresolved regulatory inconsistencies across countries and projects.

Case Studies

1. Huainan Coal Mine (China):
   • 400 ha lake, 180 GWh/year, CO₂ reduction: 184,000 tons/year.
   • Reuses degraded mining land; strong grid integration.
2. Omkareshwar Reservoir (India):
   • 1.4 MW pilot; daily water savings: 1.3 million liters.
   • Offsets 1,400 tons CO₂/year; demonstrates cost-effectiveness and rural electrification potential.

Evaluation of thermal boundary conditions in floating photovoltaic systems^[16]

Abstract

Reconciling the use of space and the production of low-carbon electricity is a key challenge in the face of changing human needs. In this context, floating photovoltaics (FPV) is proving to be a key application to colocate energy production with several activities (hydroelectricity and aquaculture). A major benefit of FPV technologies is the reduced module temperature. However, the causes of this thermal observation are still unknown. The density of the distribution of the floaters and the thermal behavior of the waterbody are two postulated roots that show positive correlations with regard to the module temperature. Therefore, there is interest in identifying precise thermal features in the application because the yield surplus promised in FPV technology is based on this cooling effect. This research aims to understand the heat mechanisms that arise in this application in comparison with ground-mounted photovoltaics (PV). A special framework based on 1-D thermal modeling and statistical classification of the results by dimensionless related features is proposed. This strategy offers a possibility to differentiate the influence of the thermal modes separately over the module temperature. First, a gain of 20% to 50% in the convective transfers is demonstrated for FPV compared with ground-mounted applications. Data exploitation associates these gains with the forced convective effects of the wind blowing on the front of the modules. Gains in free convective transfers are associated to the airflow around the module rear face, reducing the phenomenon of thermal buffering. The framework also demonstrates that the emissivity-based correlations for the radiative boundaries are in good agreement with the radiative phenomena involved in FPV. When convection preferentially cools down the module, the participating media nearby acts as a heat source, warming the installation. Thus, understanding these mechanisms in the FPV application would provide opportunities for improved temperature management through floats or array-scale optimizations.

🎯 Goal

1. To develop and validate a 1D thermal model for FPV that:
   • Separately evaluates convective and radiative heat transfers.
   • Optimizes boundary conditions based on experimental data.
   • Classifies performance using dimensionless indicators (e.g., Richardson number, clearness index).
2. To identify and calibrate correction factors that can better represent the unique thermal behavior of FPV systems.

🔍 Context

1. Floating photovoltaic (FPV) systems exhibit lower operating temperatures than ground-mounted PV, resulting in increased electrical efficiency.
2. The cooling effect is widely observed, but the physical mechanisms—particularly the role of convection and radiation—are not yet well understood.
3. Understanding the thermal boundary conditions is crucial to improving modeling accuracy and optimizing FPV design.

🚧 Research Gap

1. Existing models often use lumped U-values, failing to isolate the contribution of specific heat transfer modes (convection vs. radiation).
2. Current convective heat transfer correlations are based on ground-mounted PV, ignoring turbulence and surface characteristics of FPV setups.
3. There is no adapted model for radiative boundary conditions (e.g., sky temperature) in the context of humid microclimates over water bodies.

🛠️ Methodology and Tools

1. Experimental Site: 24 PV modules installed on a raft on a 4000 m² pond (France); data collected over 36 days in summer.
2. Sensors: Measure irradiance, wind speed, ambient temperature, humidity, panel rear temperature, and water temperature at 1-minute intervals.
3. Modeling Framework:
   • 5-layer thermal model (glass, EVA, silicon, EVA, backsheet).
   • Single-diode electrical model.
   • Computed using Modelica + Python (with sensitivity analysis, DOE, and classification).
4. Key Modeling Parameters:
   • Convective heat transfer via Gnielinski (forced) and Churchill-Chu (free) correlations.
   • Radiative exchange based on sky and water temperatures.
   • Sky temperature modeled as a function of dew point and emissivity.
5. Validation Metrics: RMSE, MBE, interquartile range (ΔIQ), skewness.

📈 Results

Convective Heat Transfer

1. Forced convection contributes the most (dominant in 47% of cases).
2. Free convection becomes relevant only under low wind speed and high panel-air temperature gradients.
3. Correction coefficients:
   • Forced convection increased by ~20% (ζ = 1.2).
   • Free convection increased by ~50% (χ = 1.5).
4. Overall improvement:
   • Temperature prediction error reduced by up to 1.5°C in mixed regimes.
   • U-values improved by ~3–8.5%, consistent with increased wind-driven cooling over water.

Radiative Heat Transfer

1. New ε-based model for sky temperature:
   • Best fit: T_sky = (0.8 + 0.005 × T_dew)^0.25 × T_amb
   • Outperforms conventional models (e.g., Aubinet, Bliss) under humid, water-adjacent conditions.
2. Water acts as a radiative heat source:
   • During night and cloudy periods, water temp > air temp.
   • Strong radiative contribution from water surface helps keep panels warm or slows cooling.

Model Accuracy

1. Corrected models outperform standard models under:
   • All convective categories (forced, mixed, free).
   • Radiative categories (night, cloudy, clear).
2. Clear-sky radiative modeling remains challenging due to:
   • High dispersion in error.
   • Need for improved cloud-cover modeling.

💡 Discussion Highlights

1. Low roughness of water enhances wind-driven turbulence, boosting convective cooling.
2. Open airspace beneath the panel rear improves natural convection (if not blocked by dense float structures).
3. Local humidity significantly alters infrared radiation balance—standard sky temperature formulas are insufficient.

⚠️ Limitations

1. Site-specific: Medium-sized inland pond in temperate Europe—results may not generalize to tropical/offshore/mountain lakes.
2. 1D thermal model: Cannot capture lateral variations or complex aerodynamics of FPV layouts.
3. Modeling excludes:
   • Module soiling effects.
   • Real-time cloud dynamics beyond clearness index proxy.

Distributed manufacturing of after market flexible floating photovoltaic modules^[17]

Abstract

Floating photovoltaic (FPV) technology is gaining prominence as a means to alleviate land use conflicts while obtaining large solar PV deployments and simultaneously reducing evaporated water loss. In this study, an open source after-market distributed manufacturing method is proposed to be applied to large flexible PV modules to make flexible FPV systems. Specifically this study considers surface floating of flexible thin film solar PV using three types of closed-cell foams: i) neoprene, ii) mincell and iii) polyethylene. The fabricated FPV underwent indoor and outdoor tests for flotation, wave resistance, temperature and resistance to algae accumulation. The average operational temperature was reduced by 10–20 °C for the FPV compared to land-based mounting indicating substantial increases in electricity output compared to ground-based deployment of any type of PV (2–4% for amorphous silicon used here and 5–10% for crystalline silicon based PV). In addition, foam-based FPV racking were also found to reduce costs of racking to $0.37–0.61/W, which is significantly lower than raft-based FPV as well as conventional land-based racking. The results of this preliminary study indicate that foam-backed FPV is exceptionally promising and should be further investigated with different foams, larger systems and more diverse deployments for longer periods to increase PV deployments.

🎯 Goal

1. To develop and test an open-source, distributed manufacturing approach for flexible FPV systems.
2. Evaluate the suitability of different closed-cell foams (neoprene, minicell, polyethylene) for flotation, temperature performance, wave resistance, and algae accumulation.

🔍 Context

1. Floating photovoltaic (FPV) systems are increasingly popular due to land-use savings, enhanced efficiency through cooling, and water conservation.
2. Existing FPV designs typically rely on rigid platforms, which are costly and less adaptable for various aquatic environments.
3. Flexible FPV, particularly using thin-film PV, presents a simpler, cost-effective alternative but remains understudied.

🚧 Research Gap

1. Limited research on flexible FPV systems using lightweight and flexible thin-film PV modules.
2. No detailed study available on using closed-cell foams as low-cost and easy-to-manufacture FPV platforms.

🛠️ Methodology and Tools

1. Design and fabrication of flexible FPV modules using commercial thin-film PV panels bonded to closed-cell foam backings.
2. Indoor flotation and wave resistance tests followed by outdoor deployment in Keweenaw Waterway, Michigan.
3. Continuous monitoring of temperature differences between land and floating setups.

📈 Results

1. Foam-based FPV significantly reduced module temperatures by 10–20 °C compared to ground-mounted systems.
2. Temperature reduction corresponded to substantial performance gains:
   • 2–4% improvement for amorphous silicon modules.
   • Expected 5–10% improvement for crystalline silicon modules.
3. Racking cost significantly lowered ($0.37–$0.61/W) compared to traditional FPV or ground-mounted racking.

💡 Discussion Highlights

1. Foam-based FPV offers substantial economic and performance benefits compared to rigid platforms.
2. Ease of deployment and cost-effectiveness are ideal for distributed, after-market manufacturing.
3. Best overall foam performance (balance of algae resistance, buoyancy, cost) was observed for polyethylene.

⚠️ Limitations

1. Preliminary short-term testing; no long-term durability or large-scale system evaluation conducted.
2. Limited variety in testing locations and climatic conditions.

Foam-based floatovoltaics: A potential solution to disappearing terminal natural lakes^[18]

Abstract

Terminal lakes are disappearing worldwide because of direct and indirect human activities. Floating photovoltaics (FPV) are a synergistic system with increased energy output because of water cooling, while the FPV reduces water evaporation. This study explores how low-cost foam-based floatovoltaic systems can mitigate the disappearance of natural lakes. A case study is performed on 10%–50% FPV coverage of terminal and disappearing Walker Lake. Water conservation is investigated with a modified Penman-Monteith evapotranspiration method and energy generation is calculated with an operating temperature model experimentally determined from foam-based FPV. Results show FPV saves 52,000,000 m3/year of water and US$6,000,000 at 50% FPV coverage. The FPV generates 20 TWh/year of renewable energy, which is enough to offset all coal-fired power plants in Nevada thus reducing carbon-emission based climate forcing partially responsible for a greater rate of disappearance of the lake. The results of this study, which is the first of its kind, indicate foam-based FPV has potential to play a crucial role in mitigation efforts to prevent the disappearing of natural lakes worldwide.

🎯 Goal

To evaluate the dual benefits of foam-based FPV on terminal lakes, specifically:

1. Water conservation potential using a modified Penman-Monteith evaporation model.
2. Energy generation using an operating temperature model validated in prior work.

🔍 Context

1. Terminal lakes are vanishing due to irrigation diversions and climate change-driven evaporation.
2. Floating PV (FPV) systems offer co-benefits: enhanced energy production and water evaporation reduction.
3. Foam-based FPV is introduced as a low-cost, fast-deployable solution for large-scale applications.

🚧 Research Gap

1. No prior studies have quantitatively assessed how foam-based FPV could be used for conserving terminal natural lakes.
2. Lack of combined modeling for evaporation reduction and energy production using foam-based FPV.

🛠️ Methodology and Tools

1. Study Site: Walker Lake, Nevada (100 km² terminal lake).
2. Data: Hourly weather and water temperature from USGS and Solcast (2017).
3. Evaporation Modeling: Modified Penman-Monteith method.
4. Energy Modeling: Foam-based FPV temperature model from Hayibo et al. (2020).
5. Simulation Scenarios: 10–50% lake surface coverage by foam-based FPV in 10% increments.

📈 Results

1. Water Conservation:
   • 52 million m³/year saved at 50% lake coverage.
   • Evaporation reduced by ~90% on covered surfaces.
2. Energy Production: 20 TWh/year at 50% coverage, enough to power 2 million homes or replace all coal power in Nevada.
3. Economic Impact:
   • $402 million/year energy value at 50% coverage.
   • $6.24 million/year water conservation value.

💡 Discussion Highlights

1. FPV can significantly help stabilize shrinking terminal lakes and ecosystems (e.g., fish habitats, waterbird populations).
2. Synergies exist with aquaculture (aquavoltaics), particularly when integrated with artificial lighting for shaded aquatic life.
3. Foam-based systems benefit from low thermal stress, reduced soiling, and low water footprint (21.5 m³/MWh).
4. Life cycle emissions are among the lowest for c-Si PV: 11 kg CO₂-eq/MWh.

⚠️ Limitations

1. No field deployment yet; all results based on simulation.
2. Durability of foam and effect of high salinity or TDS on materials not tested.
3. Additional modeling needed on light penetration, aquatic life response, and real-world deployment logistics.

The greenest solar power? Life cycle assessment of foam-based flexible floatovoltaics^[19]

Abstract

This study presents a life cycle analysis (LCA) of a 10 MW foam-based floatovoltaics (FPV) plant installed on Lake Mead, Nevada, U.S. A material inventory of the flexible crystalline silicon (c-Si)-based module involved massing and determination of material composition of the module's encapsulation layers with ATR/FTR spectroscopy and electron microscopy. The LCA was performed using SimaPro and the results were interpreted in terms of cumulative energy demands, energy payback time, global warming potential, GHG emissions, and water footprint including negative values for reduced evaporation. A sensitivity analysis was performed on the lifetime of the modules and the foam-based racking. The results show that the 30 year lifetime foam-based FPV system has one of the lowest energy payback times (1.3 years) and the lowest GHG emissions to energy ratio (11 kg CO2 eq per MW h) in c-Si solar PV technologies reported to date. In addition, the foam-based FPV system also had 5 times less water footprint (21.5 m3 per MW h) as compared to a conventional pontoon-based FPV (110 m3 per MW h). The lifetime of the foam-based racking does not affect the result, while the lifetime of the modules has a significant effect on the lifecycle impacts of the foam-based FPV plant. Foam-based FPV has a net positive impact on the environment for CO2 emissions and energy consumption if its lifetime is above 7.4 years and the technology has the potential to become the greenest c-Si-based solar PV technology if the lifetime of the modules can be guaranteed for at least 26.6 years. Future work is needed to determine the lifetimes of these systems and expand them.

🎯 Goal

1. Perform a comprehensive cradle-to-grave LCA on a 10 MW foam-based FPV system deployed on Lake Mead, Nevada.
2. Quantify EPBT, CO₂ payback time, and water footprint using empirical data, spectroscopy, and SimaPro modeling.

🔍 Context

1. While LCA (Life Cycle Assessment) studies on solar PV are well-established, they mostly focus on land-based systems.
2. Pontoon-based FPV systems have recently gained interest, but foam-based FPV, which promises drastically reduced materials and environmental impact, is largely unexplored.

🚧 Research Gap

1. No prior cradle-to-grave LCA exists for foam-based flexible FPV systems, particularly in large-scale deployment scenarios.
2. Need to quantify environmental metrics such as GHG emissions, energy payback time (EPBT), and water footprint.

🛠️ Methodology and Tools

1. Module Type: Flexible SunPower SPR-E-Flex-110 (110 W, 23% efficiency) with foam flotation.
2. LCA Tool: SimaPro 9 following ISO 14040/14044 standards.
3. Impact Categories: Cumulative Energy Demand (CED), GWP (100-year), Water Scarcity Index (WSI).
4. Scenario Analysis: Sensitivity tests on lifetimes of foam (PE) and flexible PV modules.

📈 Results

1. Energy Payback Time (EPBT): 1.3 years
2. CO₂ Payback Time: 0.82 years
3. GHG Emissions: 11 kg CO₂-eq/MWh (lowest for any c-Si PV)
4. Water Footprint: 21.5 m³/MWh (5× lower than pontoon FPV)
5. Evaporation Prevention: 3.4 million m³ over 30 years
6. Energy Generation: 650.3 GWh over 30 years
7. Water Footprint Offset: Reduced to 16.3 m³/MWh considering evaporation savings

💡 Discussion Highlights

1. Foam-based FPV has the lowest lifecycle GHG emissions and shortest EPBT of any reported crystalline-silicon PV.
2. Lifetime of modules is the critical determinant of environmental performance; foam lifetime has minimal impact.
3. Environmental superiority over pontoon and land-based PV is especially notable in water-limited regions.

⚠️ Limitations

1. Empirical data assumes 30-year lifetime; flexible PV modules only have a 5-year warranty.
2. No field durability data for foam in marine conditions; calls for further experimental validation.
3. Material inventory for flexible PV modules adapted from rigid PV due to lack of manufacturer data.

Water Conservation Potential of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics^[20]

Abstract

A potential solution to the coupled water–energy–food challenges in land use is the concept of floating photovoltaics or floatovoltaics (FPV). In this study, a new approach to FPV is investigated using a flexible crystalline silicon-based photovoltaic (PV) module backed with foam, which is less expensive than conventional pontoon-based FPV. This novel form of FPV is tested experimentally for operating temperature and performance and is analyzed for water-savings using an evaporation calculation adapted from the Penman–Monteith model. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based FPV, and thus a 3.5% higher energy output per unit power. Therefore, foam-based FPV provides a potentially profitable means of reducing water evaporation in the world’s at-risk bodies of fresh water. The case study of Lake Mead found that if 10% of the lake was covered with foam-backed FPV, there would be enough water conserved and electricity generated to service Las Vegas and Reno combined. At 50% coverage, the foam-backed FPV would provide over 127 TWh of clean solar electricity and 633.22 million m3 of water savings, which would provide enough electricity to retire 11% of the polluting coal-fired plants in the U.S. and provide water for over five million Americans, annually.

🎯 Goal

1. Develop a model that couples water evaporation reduction and energy generation from foam-based FPV.
2. Simulate large-scale deployment on Lake Mead (Nevada, USA).
3. Compare performance with standard tilted FPV systems using temperature modeling.

🔍 Context

1. Land, water, and energy systems are facing increasing stress from population growth, climate change, and food demand.
2. FPV systems, especially those mounted on large reservoirs, offer opportunities to mitigate water loss and increase renewable energy production.
3. Foam-based flexible FPV systems promise cost savings, temperature reduction, and high evaporation mitigation, yet are underexplored.

🚧 Research Gap

1. Most FPV studies focus on pontoon-based systems or submerged modules.
2. There is little modeling of foam-based FPV impacts on both water conservation and energy generation.
3. No specific operational temperature model exists for foam-supported flat FPV systems.

🛠️ Methodology and Tools

1. Experimental deployment of foam-based FPV with temperature and power monitoring.
2. Data collection using thermistors and NanoDAQ.
3. Development of a new multilinear regression model for FPV temperature using irradiance, air and water temperature.
4. Use of Penman–Monteith evaporation model with site-specific weather and lake data from NOAA and SOLCAST.
5. Simulations for 10%–50% lake surface coverage.

📈 Results

1. New temperature model (R² = 0.83):

Teo = -13.26 - 0.0875×Tw + 1.26×Ta + 0.0128×IS

1. Foam-based FPV operating temps ~10 °C cooler than tilted pontoon-based FPV.
2. Energy yield (50% coverage):

127.93 TWh/year (enough to retire 11% of U.S. coal plants)

1. Water savings (50% coverage):

633.22 million m³/year

1. Revenue potential:
   • Energy: $2.56 billion/year
   • Water savings: $220–861 million/year depending on pricing

💡 Discussion Highlights

1. Demonstrated dual-use potential: large-scale water savings and energy production.
2. Foam-based FPV significantly reduces both surface temps and evaporation.
3. Self-funding model: electricity sales could subsidize water savings infrastructure.
4. Suggests use for hydroelectric reservoirs, aquifers, and arid-region lakes.

⚠️ Limitations

1. Based on simulations and small-scale field testing.
2. No assessment of material degradation or long-term field deployment.
3. No economic cost modeling of installation, maintenance, or anchoring systems.

Prediction Model of Photovoltaic Module Temperature for Power Performance of Floating PVs^[21]

Abstract

Rapid reduction in the price of photovoltaic (solar PV) cells and modules has resulted in a rapid increase in solar system deployments to an annual expected capacity of 200 GW by 2020. Achieving high PV cell and module efficiency is necessary for many solar manufacturers to break even. In addition, new innovative installation methods are emerging to complement the drive to lower $/W PV system price. The floating PV (FPV) solar market space has emerged as a method for utilizing the cool ambient environment of the FPV system near the water surface based on successful FPV module (FPVM) reliability studies that showed degradation rates below 0.5% p.a. with new encapsulation material. PV module temperature analysis is another critical area, governing the efficiency performance of solar cells and module. In this paper, data collected over five-minute intervals from a PV system over a year is analyzed. We use MATLAB to derived equation coefficients of predictable environmental variables to derive FPVM’s first module temperature operation models. When comparing the theoretical prediction to real field PV module operation temperature, the corresponding model errors range between 2% and 4% depending on number of equation coefficients incorporated. This study is useful in validation results of other studies that show FPV systems producing 10% more energy than other land based systems.

🎯 Goal

1. To develop and validate predictive temperature models for floating PV modules (FPVMs).
2. To compare two temperature prediction models (with and without water temperature) against measured data.
3. To evaluate how module temperature influences power output and efficiency in FPV systems.
4. To benchmark FPV models against existing land-based PV temperature models.

🔍 Context

1. FPV systems are gaining popularity due to their:
   • Land-use efficiency.
   • Increased energy yield from cooling by underlying water bodies.
   • Lower module degradation rates (<0.5% p.a.).
2. Accurate PV temperature models are critical for predicting power output and system design.
3. Most existing temperature models were developed for land- or rooftop-based PV systems.

🚧 Research Gap

1. Lack of validated temperature models specifically tailored for FPV environments.
2. Previous models underperform due to exclusion of water temperature effects.
3. No comprehensive comparison of FPV vs. land-based PV temperature behaviors using large field datasets.

🛠️ Methodology and Tools

System Description

1. Location: Hapcheon Dam, South Korea.
2. Capacity: 100 kW and 500 kW FPV; compared with 1 MW rooftop PV system.
3. Sensors: Solar irradiance, ambient & water temperature, wind speed, PV module temp.
4. Data: 5-minute interval environmental and output measurements over 1 year.

Model Development

1. Two multiple linear regression models (MLR):
   • Model 1: Tm = f(Ta, GT, Vw)
   • Model 2: Tm = f(Ta, GT, Vw, Tw)
2. Least-squares error minimization used to calibrate regression coefficients.
3. MATLAB used for model development; Minitab for complex statistical fitting.

Validation and Benchmarking

1. Predicted temperatures compared against measured module temps.
2. Error metrics (Terror) calculated between predicted and real temperature values.
3. Compared with classic temperature models (Ross, Koehl, Duffie & Beckman, Skoplaki, etc.).

📈 Results

Model Formulas

1. Model 1:
   • Tm1 = 2.0458 + 0.9458Ta + 0.0215GT − 1.2376Vw
2. Model 2:
   • Tm2 = 1.8081 + 0.9282Ta + 0.021GT − 1.2210Vw + 0.0246Tw

Error Ranges

1. Model 1: Error ≈ 2.06%
2. Model 2 (includes water temp): Error ≈ 4.40%
3. Minitab Model: <1% error, but considered overfitted and complex.

FPV vs. Rooftop Comparison

1. Mean module temperature (FPV): ~21 °C (4 °C lower than rooftop).
2. 89% of FPV energy generated below 40 °C vs. 68% for rooftop.
3. Annual normalized output (h/day):
   • 100 kW FPV: 3.58 h/day
   • 500 kW FPV: 3.80 h/day
   • 1 MW rooftop: 3.28 h/day

Efficiency Model

1. ηc,FPV1 = 15.96 − 0.058 × Tm1
2. Cooling increased conversion efficiency by ~1–2% (seasonally dependent).
3. FPV showed better stability in output due to lower module temperatures.

💡 Discussion Highlights

1. Water temperature significantly improves temperature model accuracy.
2. Wind speed strongly influences module cooling performance.
3. FPV models yield lower operational temperatures than all compared land-PV models.
4. 3D plots show enhanced efficiency at lower ambient temperatures and moderate irradiance.
5. FPV systems benefit from a more favorable thermal environment even without active cooling.

⚠️ Limitations

1. Model 2 slightly overestimates cooling gains due to water temperature variable sensitivity.
2. Minitab overfits with complex interactions, limiting generalizability.
3. Data is site-specific (Hapcheon Dam), limiting transferability to different climatic zones.
4. Effects of tilt angle, float design, and module spacing not modeled.

Design of floating solar PV system for typical household on Debre Mariam Island^[22]

Abstract

Solar PV is possible alternative renewable energy resources, particularly for rural electrification. Its high demand growth may cause for land scarcity, and this will be a serious problem in countries like Ethiopia where agriculture is main source of economy and population large size. In addition to land scarcity, low efficiency of photovoltaic land installation is another problem. Hence, photovoltaic performance is relying on weather conditions, operation parameters like temperature and wind speed. Water bodies can be alternatives to install photovoltaic to the scarcest land and decrease impact of temperature on photovoltaic. To reduce the affirmation problems floating system is an alternative technology. Floating photovoltaic plants are an emerging form of PV system that floats on water bodies. Land installation of photovoltaic increases risk of PV module efficiency drops land scarcity. Therefore, the objective of this study was to design floating system for Debre Mariam Island to increases efficiency of solar cell and save land. To tackle mentioned problems floating photovoltaic installation is method used. Floating photovoltaic provides efficient energy supply and new strategy to save land. Thus, floating photovoltaic system is modeled so as to satisfy daily energy load demand of Debre Mariam Island community electric loads. The temperature and wind speed are major contributory factors for panel efficiency drops and low power output in land photovoltaic installations. 294.8 kW is the generated power output of solar floating system whereas 289.9 kW is the generated power output of land photovoltaic installation. Thus, floating PV installation increases the generated power output by 4.9 kW.

🎯 Goal

1. To design a floating solar PV system that satisfies the daily electrical load of Debre Mariam Island households.
2. To reduce the land use associated with solar PV installations in land-constrained areas like islands.
3. To improve system efficiency by lowering PV module temperatures through water-based installation.
4. To demonstrate techno-economic viability of FPV for off-grid rural communities.

🔍 Context

1. Ethiopia faces rising solar demand but suffers from:
   • Scarce arable land that competes with agriculture.
   • High solar PV temperature degradation under land-based installation.
2. Lake Tana and similar water bodies are underutilized resources for floating PV deployment.
3. Debre Mariam Island lacks grid access and depends on kerosene, charcoal, and dung for energy.
4. Floating PV offers:
   • Land preservation.
   • Cooling benefits for improved module efficiency.
   • Social and environmental benefits (e.g., reducing water evaporation and algae growth).

🚧 Research Gap

1. No floating PV designs have been implemented or assessed for Ethiopian island communities.
2. No localized design methodology using local weather, irradiance, and economic data for FPV in Ethiopia.
3. Lack of modeling that integrates ambient and water temperature, wind speed, and load-specific PV sizing.

🛠️ Methodology and Tools

System Description

1. Location: Debre Mariam Island, Lake Tana, Ethiopia (11.5742°N, 37.3614°E).
2. Users: 300 households, monastery, school, health post, water pump.
3. Daily energy demand: ~1,467.986 kWh/day.
4. Meteorological data sourced from NASA: average solar insolation = 6.14 kWh/m²/day.

Modeling Approach

1. Cell temperature modeling:
   • Used air and water temperature formulas to calculate land and water-based cell temperature.
   • Water temperature = 26.56 °C; air = 28.75 °C; sea wind speed = 9.52 m/s.
   • Cell temperature: Land = 36.70 °C; Floating = 30.35 °C.
2. Efficiency adjustment using temperature coefficient (β = -0.38%/°C).
3. Component sizing done via equations for PV array, batteries, inverter, charge controllers, and cabling.
4. MATLAB/Simulink used to simulate system performance for both floating and land-based cases.

📈 Results

Sizing Outcomes

1. PV panels: 754 mono-crystalline modules (400 Wp each).
   • Connected as 2 in series × 377 in parallel.
2. Batteries: 732 × 12V, 200Ah AGM batteries.
3. Inverters: 50 × 5 kW, 72V units.
4. Charge controllers: 47 × 100A MPPT controllers.
5. Cables: 16 mm² cross-sectional copper wiring.

Power Output Comparison

1. Floating PV output: 294.8 kW.
2. Land-based PV output: 289.9 kW.
3. Net gain from FPV: +4.9 kW due to cooling.
4. Module efficiency enhanced by cooler water temperatures and higher sea wind speeds.

Efficiency Gains

1. Floating installation reduced cell temperature by ~6.35 °C.
2. Resulted in an approximate efficiency increase of 1.5–2%.
3. Demonstrates feasibility for using water-based cooling in Ethiopian conditions.

💡 Discussion Highlights

1. FPV is a viable alternative to land-based PV in land-constrained or island regions.
2. Integrating real meteorological data (wind, solar, temperature) improves accuracy in design.
3. MATLAB/Simulink is a useful tool for simulating temperature and load-matched energy output.
4. FPV can support energy access, improve living standards, and reduce environmental impact.

⚠️ Limitations

1. No real-life system installation—design is simulation-based.
2. Cooling benefits are estimated based on empirical formulas, not validated in situ.
3. System cost and economic analysis are not included.
4. No durability or hydrodynamic analysis of floating structure under real lake conditions.

[url Title]^[23]

Abstract

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🎯 Goal

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🔍 Context

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🚧 Research Gap

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🛠️ Methodology and Tools

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📈 Results

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💡 Discussion Highlights

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⚠️ Limitations

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FPV Winter Operation - Bubbler Design

Winter water temperatures and ice prevention by air bubbling^[24]

Abstract

Air bubbling systems prevent ice formation on the surface of a body of water because the warm water at depth can be brought to the surface by rising air bubbles. The amount of heat available in the water must be known to calculate the thermal reserve. Lake temperatures are largely controlled by convection overturning, but fresh water has a maximum density at 39.2 degrees F which affects circulation and the resulting temperature. Canada's lakes are mostly of the temperate type and therefore have two turnover periods, in spring and in fall. Wind action is also very important. River water temperatures are nearly the same throughout because of mixing. Although sea water air bubbling systems have been used, careful studies must be made to ensure ice can be melted by this method. Maximum density does not occur at 39.2 degrees F, hence convection mixing may occur until ice forms at the surface. To design an air bubbling system to prevent ice formation the thermal regime of the fresh water body and its surroundings must be known. The area of influence of each jet and the size of the hole must also be known. Design studies so far have been mostly empirical. No engineering procedure has been developed. Some experimental studies have been reported and details are given of the flow patterns of various orifices for use in ice prevention at the Grand Coulee Dam. Work needs to be carried out on how the heat stored at depth under an ice surface can be used efficiently to prevent further ice growth.

🎯 Goal

1. Summarize water temperature behavior in winter conditions.
2. Present design considerations and case studies of air bubbling systems used for ice prevention in Canada and Scandinavia.

🔍 Context

1. Ice formation during winter can obstruct hydroelectric operations, FPV installations, and other aquatic infrastructure.
2. Air bubbling systems have been used to prevent ice formation by leveraging subsurface thermal reserves.
3. This technical report summarizes key observations and experimental findings on winter water temperature behavior and air bubbling system design.

🚧 Research Gap

1. Despite field use, there was no prior consolidated reference summarizing:
   • Mechanisms of air bubbling.
   • Water temperature stratification.
   • Design parameters for effective de-icing.
2. Aimed to guide field engineers implementing such systems in Canadian lakes and rivers.

🛠️ Methodology and Tools

1. Field measurements in Canadian lakes and rivers (e.g., Ottawa, Temiskaming).
2. Comparative data from Sweden, Finland, and other cold-climate sites.
3. Empirical and experimental setups tracking:
   • Depth–temperature profiles.
   • Ice formation and melting rates.
   • Bubble discharge and air flow relationships.

📈 Results

1. Thermal Resistance: Mixing resistance increases dramatically as water temperature approaches 4°C from above.
2. Shallow lakes (≤25 ft): Tend to remain isothermal in winter, facilitating efficient ice prevention.
3. Deep lakes: Experience thermal stratification; bottom water remains warmer (4°C) even when surface freezes.
4. Air bubbling effectively circulates warmer water to surface, preventing or melting ice.
5. Effective zone of influence: up to 50 m radius per hose (Nybrant, 1959).
6. Systems can prevent ice even under ambient temperatures below −20°C, depending on heat reserve and air flow.

💡 Design and Discussion Highlights

1. Air discharge increases effectiveness with nozzle depth, as flow entrains more warm water from the bottom.
2. Empirical data from installations (e.g., Prescott, ON; Slave Falls, MB) showed open water maintained all winter.
3. Optimum hole spacing and compressor size depend on:
   • Depth.
   • Flow rate.
   • Wind and ice cover conditions.
4. Identified critical parameters like heat loss rates from open water (~125–175 BTU/sq.ft./hr) vs. insulated ice-covered water.

⚠️ Limitations

1. Lacked modern CFD or real-time data acquisition.
2. Empirical results vary based on geography, water chemistry, and ambient climate.
3. No life-cycle cost analysis or automated control strategies discussed.

Design Parameters for Artificial Aeration of Ice-Covered Lakes^[25]

Abstract

Numerous lakes in cold climates require artificial aeration to maintain fish habitats during ice-cover periods. Mechanical surface aerators (“splashers”) are one type of aeration system popular in midwestern parts of the U.S. and Canada. A method is presented to represent the most important physical characteristics of splasher systems designed for small lakes through two dimensionless parameters. Data from several lakes in Wisconsin and Alberta, Canada, where splashers have been operated were used to determine a preliminary, constrained range of values for these two design parameters.

🎯 Goal

1. To develop and validate design equations and aeration strategies tailored for ice-covered stratified lakes.
2. Assess how artificial circulation can maintain oxygen concentrations and mitigate ice formation.

🔍 Context

1. In cold climates, artificial aeration is used during winter to prevent oxygen depletion beneath ice, which can lead to fish kills and ecosystem degradation.
2. Air bubbling/aeration also disrupts ice cover, which can be advantageous for certain applications such as hydro infrastructure and floating photovoltaic (FPV) deployment.
3. The study provides design criteria for such systems based on lake morphology and mixing theory.

🚧 Research Gap

1. Lack of systematic guidelines for designing aeration systems under ice-covered conditions.
2. Needed to formalize the required oxygen transfer rates, mixing volumes, and air flow rates based on lake-specific parameters.

🛠️ Methodology and Tools

1. Analysis of mass transfer equations for DO (dissolved oxygen).
2. Simulation of aeration-induced circulation volumes using stratification data.
3. Empirical validation from multiple winter-aerated lakes.
4. Parameters evaluated:
   • Air flow rate (m³/h).
   • Lake depth and surface area.
   • DO demand.
   • Ice thickness and mixing efficiency.

📈 Results

1. Effective DO replenishment and ice prevention depend on:
   • Depth of diffuser: deeper placements entrain warmer water.
   • Air flow rate: higher flows increase circulation but risk surface icing due to under-mixing.
   • Lake bathymetry: deeper lakes with small surface areas are easier to aerate.
2. Empirical results show:
   • 0.5–1.5 m³/h of air per hectare can maintain DO above critical thresholds.
   • Circulation should reach ~1.5× epilimnetic volume for complete mixing.

💡 Discussion Highlights

1. Artificial aeration can simultaneously enhance oxygen levels and reduce ice cover.
2. Must avoid supersaturation to prevent gas bubble disease in aquatic life.
3. Aeration system design must consider tradeoffs:
   • Shallow vs. deep diffuser placements.
   • Minimal vs. aggressive mixing regimes.
4. Can be adapted for multi-use systems, e.g., combining FPV de-icing with ecological benefits.

⚠️ Limitations

1. Based on simplified lake stratification models; may not apply directly to polymictic or eutrophic systems.
2. No real-time control systems modeled (e.g., automated sensors or feedback).
3. Designed primarily for oxygenation; ice prevention was an indirect benefit.

Ice load characteristics analysis and anti-icing design of a novel floating photovoltaic structure^[26]

Abstract

Existing design criteria for the floating photovoltaic (FPV) structures mainly emphasizes wind and wave environmental conditions without sufficiently taking the ice load impact into account. However, in the cold sea area, the dominant load on the FPV structure is considered to be the ice loads. This paper aims at evaluating the dynamic anti-icing performance of the novel FPV structure under ice loads. A novel FPV system with three-point mooring is proposed in this study, and the stability and mooring strength of the novel FPV system is discussed through the numerical simulation and model tests. An anisotropic ice numerical model is developed to simulate the coupled interaction between ice and the FPV structure based on finite element method-cohesive element method (FEM-CEM), and the accuracy of the ice-FPV structure coupled interaction model is verified based on a series of dynamic ice force model tests. Based on the established coupled interaction model, the dynamic ice force variation law of the proposed novel FPV are investigated under different ice velocities and thicknesses, and dynamic behaviors for mooring lines tension forces are quantitatively studied under sea ice in time domain. Meanwhile, structural damage analysis is carried out by comparing stress and strain. It is found that the component connection position on front sides of the FPV structure are areas where the damage occurs first; Afterwards, cracks are generated in connection positions on the rear side, resulting in complete fracture failure. In addition, different mooring tension states are considered to analyze the effects of ice force and mooring tension. Research results show that the slack-anchoring mooring state can be used as an anti-icing method for the novel FPV structure.

🎯 Goal

1. Propose and test a novel anti-icing FPV structure with three-point mooring.
2. Model and validate its dynamic behavior under varied ice thickness and velocities.
3. Analyze mooring tension, structural damage, and suggest anti-icing design strategies.

🔍 Context

1. Offshore and cold-climate deployment of FPV systems is expanding, but ice load impacts are often overlooked in structural design.
2. Traditional FPV designs focus on wind and wave loads, with limited attention to dynamic sea ice interactions, which can be the dominant load in polar or cold-sea regions.

🚧 Research Gap

1. Few prior studies exist on dynamic ice loading for FPV systems.
2. No validated numerical models simulating FPV–ice coupling, damage progression, or mooring behavior under sea ice.

🛠️ Methodology and Tools

1. Physical Model Tests: Wave basin experiments with scaled FPV prototype.
2. Numerical Simulation:
   • Finite Element Method + Cohesive Element Method (FEM–CEM).
   • Verified against lab-based dynamic ice interaction tests.
3. Ice Load Scenarios:
   • Ice thickness: 0.1–0.4 m.
   • Ice velocity: 0.2–0.5 m/s.
4. Design:
   • Hexagonal frame with steel floaters and anti-icing tubes.
   • Integrated 3-point mooring and flexible connectors.

📈 Key Results

1. Structural Resilience:
   • Structure withstands ice loads up to 41 kN.
   • Cracking and failure occurs only at extreme conditions (0.4 m ice thickness).
2. Mooring Analysis:
   • Tension in moorings increases up to 21700 N.
   • Slack-anchored mooring state reduces dynamic ice force by ~14%.
3. Damage Propagation: Initial failure at front-side joints → propagation to rear → full fracture.
4. Numerical Accuracy: Simulation errors <2% compared to experimental dynamic ice force data.

💡 Discussion Highlights

1. Slack anchoring is validated as an effective anti-icing design, reducing structural stress and mooring tension.
2. Ice velocity affects amplitude, while thickness affects damage severity.
3. The hexagonal, truss-based FPV foundation shows better energy dispersion than typical pontoon systems.
4. Suggests future research integrate real-time ice force sensing and FPV vibration control.

⚠️ Limitations

1. Based on modeled sea ice—real-world multi-year ice effects, brine entrapment, and thermal fatigue not evaluated.
2. No integration with actual PV modules—focus was solely on structural response.

A Guide to the Design of Air Bubblers for Melting Ice^[27]

Abstract

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🎯 Goal

1. Provide simplified design formulas for engineers to calculate:
   • Air flow requirements.
   • Velocity and turbulence characteristics.
   • Thermal mixing and ice melting rates.
2. Adapt wall jet heat transfer theory to bubble curtain behavior.

🔍 Context

1. Air bubbler systems are used to keep water surfaces ice-free, benefiting wharves, floating structures (like FPV), and navigational channels in winter.
2. This paper offers foundational guidance for designing such systems, focusing on heat transfer mechanisms, flow dynamics, and practical equations for engineers.

🚧 Research Gap

1. Prior to this work, no quantitative guidelines existed for designing air bubbler systems based on thermal dynamics and flow field behavior.
2. Existing observations (e.g., from Arctic installations) lacked theoretical underpinning and design tools.

🛠️ Methodology and Tools

1. Derived from theoretical modeling, lab data, and prior field observations in Arctic Canada.
2. Adapts empirical equations from:
   • Bulson (1961) – horizontal velocity decay from air curtains.
   • Sigalla (1958) and Sidorov (1957) – wall jet heat transfer analogs.

📈 Key Findings

1. To prevent ice formation, bubbler operation must begin before freeze-up, especially if thermal stratification is present.
2. Ice melting is driven by:
   • Upward transport of warm water (latent heat exchange).
   • Horizontal surface jet created by rising bubbles.
3. Horizontal jet max velocity (V₀) at x = d/2 is given by: ${\displaystyle V_0=1.2*(g*q*a{)}^{1/3}}$
4. Jet decay function for surface current: ${\displaystyle V/V_0=1.5*(x/d{)}^{-0.5}}$
5. Heat transfer rate for jet-induced melting modeled using Nusselt and Reynolds numbers: ${\displaystyle N=\epsilon *Cf*R*P{r}^{1/3}}$
6. Estimated required power input per meter of bubbler:
   • ~207 W/m at 20 m depth.
   • ~373 W/m at 10 m depth.

💡 Design Guidance

1. Use small, closely spaced orifices (1/8" to 1/16") for higher effectiveness.
2. Porous pipes yield higher velocities but require impractical pressures.
3. Place bubblers deep enough to tap into thermal reserves near 4 °C.
4. Even when insufficient heat exists, turbulence can delay or prevent ice cover via frazil ice dynamics.

⚠️ Limitations

1. Theoretical models assume homogeneous water; real lakes are often stratified.
2. Lacked real-time validation and ignored wave-induced turbulence or wind effects.
3. Wall-jet analogy is approximate and subject to verification.

Applicability of Air Bubbler Lines for Ice Control in Harbours^[28]

Abstract

Ice formation in the harbours in arctic region such as in Finland is a problem in winter times. The air bubblers are often used for controlling the growth of ice near the harbour pier walls. This paper gives an in-depth description of the harbour ice problem and the applicability of the bubblers. A numerical method of flow and heat-transfer is used to predict the effectiveness of the air bubblers in controlling the ice accumulation in the harbours. Empirical models of formatting and melting the ice are presented and used in the numerical solutions. It shows that the numerical method can realistically predict the ice-melting effect of the air bubblers.

🎯 Goal

Evaluate the effectiveness of air bubbler systems for harbor ice control using a combination of:

1. • Empirical heat transfer models.
   • CFD simulations.
   • Field-tested parameters from Finnish ports.

🔍 Context

1. Ice formation at harbor berth lines (especially brash and consolidated ice collars) disrupts vessel access and increases costs.
2. Air bubblers are an established yet variably successful solution for de-icing, but few computational studies exist to optimize them for Arctic and sub-Arctic ports.

🚧 Research Gap

1. Lack of numerical CFD-based modeling integrating ice melting and formation under bubbler influence.
2. Need for quantifiable metrics on thermal mixing, heat transfer rates, and effectiveness under various ice surface conditions.

🛠️ Methodology and Tools

1. Developed 2-phase CFD model using Navier–Stokes solvers with k–ε turbulence and buoyant force approximations.
2. Ice melting sub-models: Smooth ice, modified smooth ice, and rough ice based on Ashton (1979), Nyman & Eranti (2005).
3. Test case: 2000 m × 300 m harbor basin with 300 m bubbler line placed 11 m deep.
4. Evaluated air flow rates (e.g., 0.26 and 0.37 m³/s/m) under no-ice and ice-covered conditions.

📈 Results

1. Bubbler flow generated significant near-surface circulation, focused along the berth line.
2. Ice melting was concentrated within 5–15 m of the wall: Heat flux peaked at 200 W/m², sufficient to prevent ice consolidation.
3. Rough ice melted faster than smooth ice due to higher turbulence-enhanced convective heat transfer.
4. Brash ice formation and decay are self-stabilizing:
   • Thicker brash = more turbulent melting.
   • Thinner brash = more new ice formation from trapped water.

💡 Discussion Highlights

1. Demonstrated that bubbler effectiveness increases with depth and flow rate.
2. Harbor configurations with thermal effluents (e.g., warm water from power plants) can enhance de-icing when paired with bubblers.
3. Provided design formulas for heat flux, brash formation, and velocity profiles.
4. Shows that harbor de-icing is feasible using only marginally above-freezing bottom water—no need for external heating.

⚠️ Limitations

1. Focused on harbor applications—transferability to open lakes or FPV reservoirs requires further modeling.
2. Does not incorporate structural analysis or mooring interaction for floating platforms like FPV.
3. Real-world validation limited to Finnish case studies.

Ice breaking by a collapsing bubble^[29]

Abstract

This work focuses on using the power of a collapsing bubble in ice breaking. We experimentally validated the possibility and investigated the mechanism of ice breaking with a single collapsing bubble, where the bubble was generated by underwater electric discharge and collapsed at various distances under ice plates with different thicknesses. Characteristics of the ice fracturing, bubble jets and shock waves emitted during the collapse of the bubble were captured. The pattern of the ice fracturing is related to the ice thickness and the bubble–ice distance. Fractures develop from the top of the ice plate, i.e. the ice–air interface, and this is attributed to the tension caused by the reflection of the shock waves at the interface. Such fracturing is lessened when the thickness of the ice plate or the bubble–ice distance increases. Fractures may also form from the bottom of the ice plate upon the shock wave incidence when the bubble–ice distance is sufficiently small. The ice plate motion and its effect on the bubble behaviour were analysed. The ice plate motion results in higher jet speed and greater elongation of the bubble shape along the vertical direction. It also causes the bubble initiated close to the ice plate to split and emit multiple shock waves at the end of the collapse. The findings suggest that collapsing bubbles can be used as a brand new way of ice breaking.

🎯 Goal

1. Investigate and classify how collapsing bubbles interact with ice plates of different thicknesses and positions.
2. Determine which mechanism—jet impact, shock wave incidence, or reflection—is primarily responsible for ice breaking.

🔍 Context

1. Collapsing bubbles, especially those created by underwater electric discharges, can focus mechanical energy into jets and shock waves.
2. These phenomena have been used in material erosion, biomedical treatments, and underwater explosions.
3. The study explores the novel idea of using bubble collapse for ice breaking, particularly relevant for ice control in waterways, harbors, and potentially floating structures like FPVs.

🚧 Research Gap

1. No prior experimental work had demonstrated or characterized ice fracturing mechanisms caused by collapsing bubbles.
2. Needed to distinguish between damage due to jet impact and shock wave reflection for optimizing design strategies.

🛠️ Methodology and Tools

1. Bubble Generation: Spark discharge in water tank under circular ice plates (10–46 mm thick).
2. Imaging: High-speed dual-camera system (side and bottom views), LED backlight shadowgraphy.
3. Variable Parameters:
   • Ice plate condition: floating vs fixed.
   • Standoff distance: γ = bubble–ice distance / max bubble radius.
   • Ice thickness ratio: k = ice thickness / bubble radius.
4. Key metrics: jet velocity, fracture origin, elongation ratio, and wave emission timing.

📈 Results

1. Three primary mechanisms of ice fracturing:
   • Shock wave reflection at ice–air interface → tension fractures from the top.
   • Direct shock wave incidence at small γ → fractures from the bottom.
   • Jet impact alone does not cause fracture at impact site.
2. Ice breaking thresholds:
   • Fractures occur even without contact when γ is below γ_max (logarithmically increasing with bubble energy).
   • Jet speed increases with reduced ice thickness (up to ~450 m/s).
   • Floating ice plates experience higher elongation and bubble asymmetry due to heaving.
3. Fracture location vs γ:
   • High γ (>1.4): top-originating cracks from wave reflection.
   • Mid γ (~1.0): top + bottom cracks due to combined reflection and wave incidence.
   • Low γ (<0.4): ring bubble collapse → simultaneous top/bottom fracturing.

💡 Discussion Highlights

1. Shock wave reflection is the dominant fracturing mechanism, not jet impact.
2. For small γ, bubble splitting and multiple shock emissions observed—only when ice is floating.
3. Ice thickness determines whether reflected tension waves can fracture the top surface.
4. Useful for designing non-invasive ice control systems using underwater acoustic or electric sources.

⚠️ Limitations

1. Laboratory-scale experiments; scaling to real-world ice fields needs further study.
2. Does not assess environmental or ecological implications (e.g., acoustic impact).
3. Electrode-generated bubbles may contain impurities affecting reproducibility.

Design of Longitudinal Air Bubbler System Inside Ship Lock^[30]

Abstract

This study investigated the expected behavior of installing a longitudinal air bubbler system in the St Lambert Lock, Quebec, Canada to bring “warm” water from the depths of the lock chamber and reduce ice buildup on the lock walls during the winter navigation. The bubbler manifold would be installed near the bottom of the lock chamber and extend along the entire wall of the lock chamber. Compressed air would be provided to the manifold and the air would be released through a series of holes (orifices) installed along the length of the manifold. A vertical water current would be induced in the lock chamber by the rising air bubbles. The continuous supply of water to the surface should reduce ice formation along the wall of the chamber. This use of a longitudinal air bubbler system to reduce ice buildup along lock walls during the winter season is a novel use of an air bubbler system in North America in a navigation lock.

🎯 Goal

1. Design, model, and test a low-flow air bubbler manifold system to deliver warm water vertically to the lock surface.
2. Reduce ice adhesion and formation along lock walls without significant surface disturbance.

🔍 Context

1. The St. Lawrence Seaway experiences significant ice buildup during winter, obstructing vessel navigation in locks.
2. While traditional high-flow air screens are used to move ice horizontally, this study investigates a low-flow, longitudinal air bubbler system designed to reduce ice formation along lock walls by lifting warmer water from depth.

🚧 Research Gap

1. No known design optimization or field studies exist for longitudinal (wall-parallel) bubbler systems in North America.
2. Unknown temperature stratification within lock chambers during winter makes heat transfer-based design impractical.

🛠️ Methodology and Tools

1. Software: BUB300 (USACE) used to simulate manifold air flow, plume behavior, and uniformity of orifice discharge.
2. Design Scenarios:
   • Orifice diameter: 0.7 mm to 1/4 in.
   • Orifice spacing: 4–16 ft.
   • Manifold submergence: 20–60 ft.
3. System tested: 3-inch manifold, 1/16" orifices, 8-ft spacing.
4. Performance criteria included:
   • Orifice flow rate uniformity.
   • Plume surface spread coverage.
   • Compressor sizing (30–70 psi).

📈 Results

1. Uniform air discharge achieved with ≤3% variation using 3″ manifold and 8-ft spacing.
2. Surface plume coverage optimized at ~1:1 ratio of plume width to spacing for 1/16" orifice.
3. Shallower manifolds (<40 ft) yielded insufficient spread due to reduced vertical entrainment.
4. Final design: 3-in manifold reduced to 2-in in field for cost savings without performance loss.

💡 Discussion Highlights

1. Gentle vertical currents from rising bubbles suppressed ice formation with minimal turbulence.
2. Design validated against Finnish Saimaa Canal installations.
3. Observed side benefit: mild horizontal flow moved floating ice to lock center, improving navigability.
4. Avoided deep, high-power designs to limit energy use and system complexity.

⚠️ Limitations

1. No internal measurement of water temperature gradient.
2. Uncertain how proximity to lock wall affects vertical plume expansion.
3. Did not test interaction with aquatic biofouling or long-term durability under sedimentation.

Numerical simulation of air bubbler systems^[31]

Abstract

The use of air bubbler systems to suppress ice formation is a technique that has been applied in a variety of situations with varying degrees of success. In 1974, two-dimensional line source bubbler systems were analyzed by G. D. Ashton in an effort to make available a tool that may be used in the design of a bubbler installation. That analysis was a steady-state evaluation of the melting rate of an ice cover above a bubbler system predicted on the basis of the input variables (depth, air discharge rate, water temperature). In actual operation, however, a bubbler 'sees' changing conditions such as diurnal and longer-term weather conditions, varying water temperatures and depletion of the available thermal reserve.The simulation presented herein uses the steady-state analysis developed earlier by Ashton and steps it in time with each new condition determined from the results of the previous time step. In this sense the analysis herein may be considered quasi-steady.Results of the simulation are presented for an example case for a winter in Superior, Wisconsin, and illustrate the variation in width of open water area with changing weather conditions with good comparison to field observations.

🎯 Goal

1. To develop a time-stepped (quasi-steady) numerical simulation for designing and evaluating air bubbler systems used to suppress ice formation.
2. To incorporate variable weather, water temperature, and thermal reserve depletion into bubbler system analysis.
3. To assess how operating strategies (e.g., intermittent use) influence ice suppression efficiency and open water width.
4. To provide a tool for optimizing diffuser geometry, orifice sizing, and heat transfer effects in winter applications.

🔍 Context

1. Air bubbler systems are widely used in cold regions to suppress ice formation in harbors, locks, and reservoirs.
   • By inducing convective plumes of warm water via rising bubbles, these systems melt ice or prevent it from forming.
2. Early analyses (Ashton, 1974) assumed steady-state conditions and simplified geometries.
3. Real-world operations face dynamic environmental changes, such as diurnal temperature swings and variable thermal reserves.

🚧 Research Gap

1. Prior models were static and did not simulate:
   • Time-varying thermal reserves and weather inputs.
   • Realistic heat exchange with dynamic water-ice-air interfaces.
   • Practical diffuser design constraints (spacing, flow rate, orifice size).
2. No validated model existed to simulate continuous or intermittent bubbler operation in a real lake or harbor.

🛠️ Methodology and Tools

Model Architecture

Simulation structured in 4 coupled modules:

1. Diffuser line analysis:
   • Calculates airflow and pressure loss using iterative discharge equations.
   • Parameters: manifold length/diameter, orifice size/spacing, submergence depth, compressor pressure.
2. Plume and heat transfer analysis:
   • Computes water entrainment, rising velocity, and convective plume width using Gaussian velocity profiles.
   • Uses Kobus (1968) formulas for plume spread and Ashton’s heat transfer coefficients for turbulent jets.
3. Ice melting analysis:
   • Calculates local melting rate using 1D heat balance between impinging warm water and ice cover.
   • Includes conduction through ice and air boundary layer.
4. Thermal reserve depletion:
   • Calculates energy removal from the water body as heat is used to melt ice.
   • Scales down the temperature profile for next time step.

Simulation Parameters

1. Heat transfer model validated with field data (Keribar 1976, Gardon & Akfirat 1966).
2. Input data: air temperature (daily), water temperature profile, site dimensions, and diffuser layout.
3. Field case: Howards Bay, Superior, WI (1973–74) with a 1 km bubbler line.

📈 Results

Validation Example

1. Site: Howards Bay, Lake Superior.
   • Bubbler: 1,000 m line installed 30 m offshore at 10 m depth.
   • Duration: 40 days (Jan–Feb 1974).
2. Open water width and ice thickness evolution closely matched observed field data.
   • Best match occurred when thermal depletion was disabled—likely due to unaccounted industrial warm effluent.
3. Ice melt rate and open water area depended on:
   • Initial water temperature profile.
   • Air discharge rate (Qₐ), submergence depth (H), and spacing (S).

Plume & Heat Transfer Findings

1. Surface plume width increased with diffuser depth and air flow rate.
2. Heat flux concentrated under the centerline; dropped off with radius ∝ (y/b)^−0.56.
3. Only ~1.5% of total induced heat flux (Qₐ) actually melted ice.

Engineering Guidance

1. Effective orifice spacing: S ≤ H/2 (typically ~1.5–2 m for 3–5 m depth).
2. Deeper bubblers = wider plume and more uniform melt area.
3. Even modest compressors can suppress ice if plume entrainment is optimized.

💡 Discussion Highlights

1. First validated numerical model for bubbler-driven ice suppression.
2. Demonstrated quasi-steady simulation using real environmental inputs.
3. Supports design of diffusers with:
   • Uniform pressure and airflow.
   • Efficient thermal delivery.
   • Practical energy input matching system needs.
4. Highlights diminishing returns from thermal reserve as heat is drawn from the water body.

⚠️ Limitations

1. Thermal depletion handled via simplified uniform scaling of the water profile.
2. Experimental coefficients (from air jet studies) may not generalize to all aquatic conditions.
3. No wave/wind effects modeled (which may impact plume spread).
4. Does not simulate refreezing conditions after bubbler shutdown.
5. Needs more validation in deeper reservoirs and with varied diffuser layouts.

Melting Ice with Air Bubblers^[32]

Abstract

No Abstract in the manuscript

🎯 Goal

1. To present practical design principles for using air bubbler systems to melt or suppress ice formation.
2. To consolidate findings from previous experimental and theoretical studies (notably Ashton 1974, 1978, 1979).
3. To provide engineers and site planners with guidance on siting, thermal calculations, and diffuser design.
4. To illustrate the energetics, limitations, and heat transfer mechanics of bubblers with real-world examples.

🔍 Context

1. Air bubbler systems have been used for over 65 years to suppress ice near:
   • Harbors, piers, docks, and navigation locks.
   • Icebreaking and ship storage zones.
2. Bubblers function by lifting warmer bottom water to the ice–water interface using rising air bubbles.
3. While effective, designs were historically ad hoc due to lack of rigorous engineering analysis.
4. New insights from field and lab studies (Ashton 1970s) enable systematic simulation and planning.

🚧 Research Gap

1. Limited access to validated equations for:
   • Heat transfer between plumes and ice.
   • Entrainment and plume width.
   • Horizontal flow and thermal depletion modeling.
2. Site-specific conditions (depth, circulation, snow cover, freezing index) were rarely incorporated into past designs.
3. No universal tools existed to determine how much ice can realistically be melted under different environmental constraints.

🛠️ Methodology and Tools

System Physics and Site Conditions

1. Key parameters:
   • Water depth and bottom temperature (often << 4°C).
   • Flow/circulation affects heat depletion and plume drift.
   • Ice type (stationary or moving), thickness, and freezing degree-days.
   • Snow cover (important insulator) affects net atmospheric heat flux.
2. Site-specific thermal reserve estimates must precede bubbler deployment.

Mechanical Design

1. Compressors: Deliver 0.0094–0.71 m³/s (20–1500 ft³/min) at 0–50 psig.
2. Piping:
   • Supply line: Must maintain pressure and minimize friction losses.
   • Diffuser line: Orifice spacing ≈ half submergence depth (H/2).
3. Orifice equation:
   • Qa = Cd * A * sqrt(2ΔP/ρ)
4. Typical orifice sizes: 1/16–1/8 in. for uniform discharge.

Plume Mechanics

1. Plume velocity modeled as a Gaussian distribution.
2. Plume width at surface (2b) scales with air flow and depth:
   • 2b = 0.364(H + 0.8)Qa^0.3
3. Entrainment delivers warm water to surface:
   • Qw ≈ 2.28 * e^0.5H * Qa^1.3
4. Heat transfer coefficient under impingement region:
   • hb ≈ 6888 * H^-0.34 * Qa^0.16 (W/m²·°C)

Thermal Modeling

1. Total heat delivered:
   • G = Qw * cp * (Tavg - Ts)
   • Ts = 0°C under ice.
2. Heat available to melt ice:
   • qb = hb * (Tavg - Ts)
3. Ice thinning rate:
   • dq/dt = qb / (ρi * Lf)

📈 Results

Case Studies and Values

1. At Qa = 0.001 m²/s, H = 10 m, Tavg = 0.1°C:
   • hb = 979 W/m²·°C → qb = 97.9 W/m²
   • Ice melting rate ≈ 2.76 cm/day.
2. Equilibrium thickness with –25°C air temp:
   • 28 cm thick ice maintained (if qb = 200 W/m²).

Performance Table Insights

1. Higher depths and airflow yield:
   • Wider impingement region.
   • Greater entrainment.
   • Higher heat flux per unit length.
2. Overuse may quickly deplete local thermal reserves.

Operation Modes

1. Two recommended strategies:
   • Maintain a thin ice layer (vs. open water) to conserve thermal reserve.
   • Intermittent operation (e.g., match coldest periods) to extend usable energy.
2. Designs must account for thermal depletion and flow-induced plume drift.

💡 Discussion Highlights

1. Thermal reserves are often overestimated—field measurements are essential.
2. Even low-flow bubblers can melt ~1 inch/day if depth and design are optimized.
3. Detailed sizing tables and heat formulas allow pre-installation performance forecasting.
4. Best use: localized ice suppression rather than entire water body deicing.
5. Strategic operation (timing and area targeting) maximizes utility.

⚠️ Limitations

1. Assumes plume entrainment follows simplified Gaussian and log scaling.
2. Does not model wind or wave interference, or biofouling of diffuser lines.
3. Thermal depletion modeled as 1D linear decay—real systems may behave non-linearly.
4. Ambient snow and solar irradiance effects not dynamically included.
5. Real-time sensor feedback (e.g., temperature, flow) not integrated into system logic.

Design of an Aeration System to Enhance Trout Habitat in Holland Lake, MN^[33]

Abstract

Holland Lake, a small but deep mesotrophic lake in the Twin Cities Metropolitan Area, has been considered by the Minnesota Department of Natural Resources, Division of Fisheries, for stocking with brown trout. Holland Lake, with a surface area of 0.14 km2 (35 acres) and a maximum depth of about 18.8 m (61 ft) consists of two shallow bays covered with rooted macrophytes and a deep main basin. The deep basin is thennally suitable for brown trout. However, due to a high oxygen depletion rate in summer, the lake becomes anoxic below the surface mixed layer from late June to early July. The rate of oxygen depletion below the surface mixed layer, based on field measurements, was estimated to be about 0.47 mg/day·l. Field studies conducted in the summers of 1999 and 2000 indicated that only horizontal advection processes could explain the observed high dissolved oxygen (DO) depletion rates. Density currents transport low DO water with high BOD into the deep basin metalimnion. These currents from the shallow bays were attributed to the temperature regimes of the shallow bays and groundwater flow through the lake. To improve brown trout habitat in Holland Lake, an aeration system has been designed based on the observed sumnler conditions. The aeration system comprises two bubble curtains along the border of the shallow bays to enhance mixing in the shallow bays and one metalimnetic aerator in the deep basin. The bubble curtains deepen the surface mixed layer down to 4 m, and prevent the fomlation of density currents from the shallow bays into the deep basin.

🎯 Goal

1. To design an aeration system that enhances the suitability of Holland Lake for brown trout during summer stratification.
2. To prevent anoxia in the metalimnion while preserving the lake's thermal structure.
3. To test a combined system of air bubble curtains and a metalimnetic aerator to maintain optimal temperature and dissolved oxygen levels.
4. To evaluate intrusions from shallow bays and reduce oxygen demand in the deep basin.

🔍 Context

1. Holland Lake is a small (0.14 km²), deep (18.8 m) mesotrophic lake in Minnesota.
   • It features two shallow macrophyte-filled bays and a deep central basin.
   • The lake stratifies in summer, causing anoxia in the metalimnion, making it unsuitable for trout.
2. Brown trout require DO > 5 mg/L and T < 21 °C.
3. Intrusion flows from shallow bays transport low-DO water and organic material into the deep basin.
4. Harvesting macrophytes or dredging is costly and ecologically disruptive.

🚧 Research Gap

1. Prior lake aeration strategies focused on whole-lake or hypolimnetic aeration without addressing:
   • Intrusion-driven DO depletion in deep basins.
   • Thermal layering needed for coldwater fish habitat.
2. No prior metalimnetic aeration system integrated with bay-level bubble curtains for selective control.
3. Lack of practical engineering design guidance for coupled lake-bay aeration strategies.

🛠️ Methodology and Tools

System Configuration

1. Two bubble curtains placed between the shallow bays and the deep basin (~4 m depth).
2. One vertical metalimnetic aerator located in the deep basin (4–9 m depth range).
3. A shelter hosts all blowers and compressors, supplying air via polyethylene pipes.

Design Calculations

1. Bubble curtains:
   • Pipe diameter: 2" with 1 mm orifices spaced 1.5–2 m apart.
   • Designed for 12-hour turnover of 393,000 m³ surface mixed layer.
   • Airflow rates: 3.5–5.8 L/s per line.
2. Metalimnetic aerator:
   • Riser tube height: 10 m; diameter: 2.3 m.
   • Entrainment flow: ~1.25 m³/s → 1.9-day renewal for 210,000 m³ volume.
   • Oxygen transfer efficiency (OTE): ~20%.
3. Tools used:
   • Heat budget simulations (multiple years).
   • Gaussian plume entrainment models.
   • ASCE and EPA guidelines for aeration system sizing.

Monitoring and Criteria

1. Design DO depletion rate: 1.2 mg/L/day (2.5× observed max of 0.47 mg/L/day).
2. Temperature and DO targets set by Minnesota DNR trout habitat guidelines.
3. Field validation in 1999–2000 used stratified DO and temp profiles and groundwater estimates.

📈 Results

System Performance Simulations

1. Heat budget models showed that:
   • Whole-lake or deepened epilimnion mixing exceeds trout temp thresholds (>21°C).
   • Selective metalimnetic aeration maintains suitable T and DO.
2. Bubble curtains:
   • Disrupt intrusive flows from shallow bays (carrying BOD).
   • Maintain a stable 4 m epilimnion to protect the metalimnion.

Engineering Findings

1. Flow modeling:
   • Used Fujie, Goossens, and Taggart–McQueen models for airflow–entrainment correlations.
2. Blower layout:
   • Three R6 GAST blowers in series for bubble curtains.
   • Six AQ63 rotary vane compressors (2 standby) for aerator.

Cost Estimates

1. Total system cost ≈ $100,000 USD.
   • Bubble curtains: ~10% of cost.
   • Aerator and infrastructure (compressors, pipes, shelter): ~90%.

💡 Discussion Highlights

1. Combined system approach (curtains + metalimnetic aerator) enhances DO while preserving stratification.
2. Bubble curtains play a dual role: physical barrier and entrainment tool.
3. Metalimnetic aeration improves habitat in a volume-efficient, energy-efficient manner.
4. Strong emphasis on staged construction and adaptive management based on monitoring data.
5. System is modular and scalable for similar mesotrophic lakes.

⚠️ Limitations

1. Real-world biofouling, snow cover, and climate variability not deeply modeled.
2. Field testing of plume behavior and DO uplift pending full deployment.
3. Long-term maintenance (especially diffuser cleaning) depends on diver accessibility.
4. Nutrient resuspension in shallow bays due to curtain mixing needs monitoring to prevent eutrophication.

AIR BUBBLER SYSTEMS TO SUPPRESS ICE^[34]

Abstract

No Abstract

🎯 Goal

1. To develop a theoretical and practical framework for designing air bubbler systems to suppress or melt ice in cold regions.
2. To model heat transport, water entrainment, and ice melting under various environmental and system configurations.
3. To provide design procedures based on airflow, diffuser depth, plume behavior, and site characteristics.
4. To inform U.S. Army Corps of Engineers projects aiming to extend the Great Lakes–St. Lawrence Seaway navigation season.

🔍 Context

1. Ice buildup in harbors, channels, and industrial facilities can impede winter operations.
2. Bubbler systems use compressed air to lift warmer bottom water to the surface, melting ice or preventing formation.
3. Compared to velocity systems (e.g., propeller-driven flow), bubblers:
   • Are more energy-efficient.
   • Maintain higher heat transfer velocities near the ice.
   • Deliver energy more uniformly over wider areas.
4. Existing bubbler installations were often ad hoc, lacking rigorous thermal or hydraulic modeling.

🚧 Research Gap

1. Previous studies lacked:
   • Quantitative methods to design diffuser size, spacing, and airflow rates.
   • Predictive models of convective plumes and induced circulation.
   • Dynamic thermal reserve estimation under realistic stratification conditions.
2. No clear procedure for calculating effective plume reach, melting rates, or long-term depletion of heat reserves.

🛠️ Methodology and Tools

Model Components

1. The report develops a coupled, semi-analytical model including:
   • Vertical entrainment of water into the bubble plume.
   • Horizontal spreading beneath the ice.
   • Heat transfer at the ice-water interface.
   • Exhaustion of the lake or river’s thermal reserve.

Key Equations and Concepts

1. Air discharge rate per unit length:
   • Qa (m²/s), related to orifice size and pressure via Q = Cd·A√(2ΔP/ρ).
2. Vertical water entrainment:
   • Qw(H) ≈ 5.533·Qa⁰·⁵·(H + x₀)⁰·⁵ [with x₀ ≈ 0.8 m].
3. Plume width at surface:
   • 2b ≈ 2(H + x₀)Cc·Qa⁰·¹⁵ [Cc ≈ 0.182].
4. Heat delivered:
   • G = Qw·cp·(T - Tm) [with cp = specific heat of water].
5. Heat transfer coefficient at ice interface:
   • hb ≈ 6888·H⁻⁰·³⁴·Qa⁰·¹⁶ (W/m²·°C).
6. Melting rate:
   • dq/dt = qb / (ρi·Lf), where qb is surface heat flux.

System Types and Site Considerations

1. Point source vs. line source diffusers.
2. Site geometry, winter thermal regime, and depth critical to performance.
3. Entrainment and circulation models include:
   • Stable "filling" model: deep lakes slowly mixed.
   • Overturning model: convective cells (~2.5×H wide).
4. Risk considerations: ice damage, vessel interference, sediment disturbance.

📈 Results

Design Guidance

1. Orifice spacing: ≤ H/2.
2. Optimal diffuser depth: deeper systems entrain more water and create wider plumes.
3. Airflow rates: design varies from 0.0001–0.01 m²/s depending on target area and heat availability.
4. Induced plume radius at surface: ~5–15 m depending on H and Qa.
5. Heat flux to ice: ~50–400 W/m² depending on flow and water temperature.

Melting Rates and Thermal Reserve Usage

1. Melting rates: up to 2.76 cm/day with 0.1 °C water.
2. 1°C water temp with good design can maintain ~28 cm thick ice even under −25°C air.
3. 1.5–3% of total energy delivered actually melts ice—the rest is lost to ambient water mixing.

System Examples

1. Case study: Howards Bay, Lake Superior.
   • 1,000 m bubbler line in 10 m deep water successfully kept channel ice-free for 40 days.
2. Simulated vs. measured open water width showed good agreement using the quasi-steady model.

💡 Discussion Highlights

1. Deeper bubblers provide:
   • Better horizontal reach.
   • Higher convective melting efficiency.
   • Slower exhaustion of heat reserves.
2. Bubble-driven flows have nearly constant vertical velocity—ideal for convective heat delivery.
3. Induced horizontal jets spread energy ~5–10 m from diffuser axis, decreasing with radius.
4. Gaussian plume models and empirical entrainment laws enable adaptable site-specific designs.

⚠️ Limitations

1. No dynamic wave, wind, or sediment modeling included.
2. Thermal reserve estimates may vary due to sediment heat capacity assumptions.
3. Does not include salinity or fouling effects (important in estuarine systems).
4. Analytical models rely on parameters (e.g., Cb, Cc) from limited experiments.
5. Effectiveness drops quickly with low water temperatures or shallow depths.

High-Flow Air Screens Reduce or Prevent Ice-Related Problems at Navigation Locks^[35]

Abstract

A variety of techniques have been developed in the past to prevent ice from interfering with navigation lock operations. Ice, either broken and floating or frozen in place, can affect the use of the upper lock approach, the lock chamber, the gates and machinery, and the floating mooring bitts. Wind, current, tow traffic, and frozen-in-place ice fill the locks with ice, hampering operations. Winter navigation and lock operations on the inland waterway are affected by ice. Existing methods for handling ice problems have met with various degrees of success. The options available to lock operators include ice lockages, increased tow entrance speeds, use of emergency bulkheads as spillways, air bubblers, barges as deflectors, gate fanning, steam applications, compressed air lines, pike poles, chipping, electric heaters, restricted tow width, coatings, hot water applications, towboat assistance to break ice or induce flow, and modification or cessation of gate and lock operations. This article describes the best technique developed that has been effectively demonstrated at several navigation locks in the United States. The system consists of an improved bubbler system that combines three air manifolds at various locations within the lock to control and move the ice, allowing normal lock operations even in the most severe winter conditions.

🎯 Goal

1. To design and demonstrate an improved high-flow air bubbler system for navigation locks to:
   • Prevent or remove brash ice accumulation.
   • Maintain operability of gates, lock chambers, and floating components during winter.
2. To show that strategically placed, high-volume air manifolds outperform traditional low-flow systems.
3. To provide a field-tested guide for installation, compressor sizing, and manifold layout.

🔍 Context

1. Ice hampers navigation lock operations in U.S. inland waterways by:
   • Freezing gate recesses, mooring bitts, and gate rollers.
   • Packing brash ice into lock approaches, gates, and control structures.
   • Damaging infrastructure and slowing lockage times.
2. Lock operators previously used:
   • Ice lockages, pike poles, towboat wheel wash, heating systems, and basic bubblers.
3. These were marginally effective, labor-intensive, and often unsafe.
4. A complete high-flow air bubbler system was developed to offer more reliable and safer operation.

🚧 Research Gap

1. Existing low-flow bubbler designs lacked:
   • Uniform air distribution.
   • Strategic diffuser layout (gate recess, sill, upstream ice screen).
   • Scalable compressor systems.
2. Operators had no guidance for:
   • Pipe sizing for airflow delivery.
   • Orifice placement and manifold spacing.
   • Integrating control valves and compressors into lock operations.

🛠️ Methodology and Tools

System Design: Three-Manifold Approach

1. 1. **Gate recess flusher**:
   • Clears ice from gate recess walls so gates can fully retract.
   • Orifice spacing: varies (closer near quoin); 9 orifices typical.
2. 2. **Air screen**:
   • Located at the sill, upstream of miter gates.
   • Clears a path across chamber width.
   • 96 ft manifold with 13 orifices (for 110-ft lock width).
3. 3. **Diagonal deflector**:
   • Positioned in upper approach.
   • Deflects incoming ice before it reaches gate area.
   • ~200 ft long manifold with 26 orifices.

Air Supply Design

1. Compressor capacity: ≥750 cfm (0.35 m³/s) for full system.
   • Only one manifold used at a time.
2. Pipe sizing:
   • Supply line: 3" (min); 4" for longer runs (>150 m).
   • Orifice discharge: ~30 cfm/orifice (0.014 m³/s).
3. Orifice diameter: 3/8" (9.5 mm), drilled in stainless plugs.
4. Controls:
   • Manifolds individually selectable via remotely operated valves.
   • Inline check valves prevent backflow freezing.

📈 Results

Installation and Performance

1. Installation time: ~240 man-hours per lock chamber (with components pre-fabricated).
2. Compressor rental used to avoid upfront capital expenditure.
3. Regular operation kept orifices from silting or clogging.
4. Average air usage: 1 hour of compressor time per lockage.
5. Ice removed:
   • From gate recesses (retraction enabled).
   • From lock chamber (screen cleared forebay).
   • From upper approach (deflector steered ice toward spillway).
6. Starved Rock Lock (IL) performance over two winters:
   • Compressor runtime reduced by 8.7%.
   • Fuel use stable (~2,900 gal).
   • Lockages increased by >2× (248 → 586).
   • Operator satisfaction high; safety improved.

💡 Discussion Highlights

1. System works best when:
   • Only one manifold operates at a time (to ensure max airflow).
   • Air delivery matches orifice capacity to avoid pressure drop.
2. Operator training essential—each manifold has a specific purpose.
3. Year-round maintenance (e.g., periodic bubbling) prevents plugging.
4. Visual indicators for valve state improve usability and prevent misuse.

⚠️ Limitations

1. Initial capital cost (~$75–100k per lock), though seasonal rental lowers entry barrier.
2. Only tested at 110-ft locks—scaling to larger or smaller locks needs further design.
3. Operation effectiveness depends on ice type (frazil, brash, solid) and wind conditions.
4. Orifice clogging possible if sediment control or backflushing not maintained.
5. No modeling included for dynamic hydraulic effects or wake-induced flow.

[url Title]^[23]

Abstract

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🎯 Goal

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🔍 Context

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🚧 Research Gap

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🛠️ Methodology and Tools

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📈 Results

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💡 Discussion Highlights

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⚠️ Limitations

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H2O cooling function of Solar PV (Floatovoltaic)

• ---

An active cooling system for photovoltaic modules(2010)^[36]

• Electrical Efficiency of the PV cell is greatly affected by operating temprature of the PV cell
• Designed parallel air ducts for inflow and outflow for uniform airflow distribution
• Compared the active cooling of PV cell with and without an active cooling system
• Developed a simulation model for comparing the actual on site results with the simulation results

Enhancing the performance of photovoltaic panels by water cooling(2013)^[37]

• ---
• P-V Characteristics are dependent on the temperature and output voltage of solar panel and are inversely proportional to each other
• When temperature starts increasing the efficiency to produce electricity for the same irradiance level decreases
• Performed many experiments using water and air as a coolant for cooling the solar panels and analyzed that water is the best and cheap coolant
• Developed heating rate and cooling rate mathematical model to find the exact moment when cooling needs to start for the cooling process
• ---

Assessment of the Operating Temprature of Crystalline PV Modules Baesd on Real Use Conditions(2013)^[38]

• Found the optimal operating mode for converting electrical energy from solar panels
• Created standard operating procedure using P-V characterstics
• Given the results that electricity production depends on ratio of voltage/ volatge at maximum power point
• ---

Improved Power Output of PV System by Low Cost Evaporative Cooling Technology(2013)^[39]

• In this paper the performance of the PV Module is enhanced by evaporative cooling technology. In this the air from the blower is passed thorigh a cool wet pad and which in turn coos down the rear part of the PV module.
• Various factors affecting the evaporation like relative humidity, air temperature, sir movement and exposed surface area were considered during cooling down process of the PV module.
• Different equations for calculating Voc, Isc, IL and Is were introduced and how this equations are dependent on temperature was shown.
• Different graphs depending on Temperature and Vic , Isc and Efficiency has been studied and how with the change in temperature the Voc and Isc varies which ultimately varies the efficiency.
• ---

Improving of the photovoltaic / thermal system performance using water cooling technique (2014)^[40]

• The cooling of PV panels is done by water circulating at PV module rear surface.
• A mathematical modeling has been carried out to compare with the experimental set up.
• The cooling of PV module is done by using a heat exchanger and cooling fan.
• Different cases has been studied by changing the mas flow rate of fluid and Maximum ambient temperature MAT.
• ---

Experimental evaluation of the performance of a photovoltaic panel with water cooling(2014)^[41]

• Rear cooling of PV Module has been performed to decrease the cell temperature and increase the efficiency.
• Graph for power output vs irradiance for both normal and hybrid model has been plotted.
• Reduction in temperature with change in the mass flow rate has been studied.
• ---

Increasing solar panel efficiency in a sustainable manner(2014)^[42]

• This paper discussed about the cooling and cleaning of PV modules by water for better efficiency.
• The kinetic energy of the water rolling down the panel and falling into the tank has been used along with a Hydraulic RAM pump tp pump the water to the top tank. By this process the minimum energy is required to pump the water for cooling and cleaning purpose.
• Comparison has been made on the efficiency of the panel covered by dust and dry panel with panel cleaned and cooled by water. The overall efficiency of the panel was increased by 14%.
• ---

Study on performance enhancement of PV cells by water spray cooling for the climatic conditions of Coimbatore, Tamilnadu(2015)^[43]

• Solar irradiance for the particular site has been calculated for the year.
• Based on irradiance the PV module back and rear temperature has been calculated through a mathematical modeling.
• Mathematical calculation for the time taken(t) for the cooling of panels at different flow rate has be derived.
• Along with cooling of PV modules how the thin layer of water reduces the reflection losses and cleans PV panels for better efficiency.
• ---

Experimental Assessment of PV Module Cooling Strategies(2015)^[44]

• Factors that contributes to the efficiency of the PV module has been studied
• A pilot study was conducted to investigate at which tilt angle PV module produces maximum surface temperature and how it effects the output power
• The study also revealed that the cell temperature and the back surface temperature are different and back surface temperature is a good approximation of the actual cell temperature.
• Two different cooling set up were compared with a non cooling system to find the difference in temperature and power output.
• ---

Experimental Study on Efficiency Enhancement of PV Systems With Combined Effect of Cooling and Maximum Power Point Tracking(2016)^[45]

• The efficiency of the PV module is studies by taking into consideration the PV module temperature and Maximim power point tracking.
• A mathematical formula that defines the efficiency of the solar panel has been introduced.
• A mathematical formula that can be used to calculate the temperature of the PV module has been introduced.
• Here the cooling of the PV module has been done by passing water through the copper pipes fitted at the rear side of the PV module.
• In the cooling process the flow/loop of water is maintained by the process of thermosiphon. The use of pump has been avoided in this process.
• The complete set up has been tested under different conditions. Through the process the efficiency could be increased to 8.95% to 10.66%.
• ---

Efficiency improvement of solar PV panels using active cooling(2012)^[46]

• This apaper intends to improve the efficiency of the PV Panel by active cooling to reduce the losses due to temperature and considering and decrease reflection losses to some extent.
• This paper considers different aspects related to solar power plant and its efficiency improvement like photovoltaic losses, methods to reduce losses, active cooling system, soil temperature modelling & design of under ground tunnels.
• The paper also explains hoe the flow of water on the PV module decreases the temperature and acts as a better refractive index material between glass and air.
• A mathematical calculation for the thermal modelling of PV panel has been introduced.
• A practical calculation has been made to calculate the amount of energy produced, the energy required in water circulation and the net energy produced. *An economic calculation has also been made to calculate the amount of money invested and how fast it can be retrieved by using the above technology.
• ---

Solar water heating system and photovoltaic floating cover to reduce evaporation: Experimental results and modelling(2017)^[47]

• In this paper, floating PV is used for covering the pond and heating the water for industrial purposes. Detailed formulation is provided.
• The pond with floating covers water evaporation reduction was greater than 90% with respect to an uncovered pond.
• In copper mining there is a significant potential for using solar energy to heat solutions in electro-winning and for washing copper cathodes. In order to improve the leaching efficiency of sulfide minerals, a high temperature is required to improve the mineral process like leaching because the extraction increases with the temperature.
• Proposed a simulation model for energy efficiency assessment.
• ---

Technical-economic study of cooled crystalline solar modules(2016)^[48]

• The aim of the paper is to study the techno-commercial aspects of a solar dydtem with evaporative cooling technology.
• The set up considers various technical aspects of the location and pv module like voltage and cuurent, moisture content of air, global irradiation, wind aspect etc.
• It also emphasized on the water evaporation due to cooling process and also concluded that in case of poly-crystalline solar module cooling system was switched on less frequently.
• Economic aspect was studied for the set up on different countries considering the amount involved , inflation, feasibility and delivery price of the electric energy.
• ---

A Combination of Concentrator Photovoltaics and Water Cooling System to Improve Solar Energy Utilization(2013)^[49]

• Water cooling system in concentrator PV is shown with schematic diagrams
• Optimal time of start/stop operation of cooling system is presented
• Neural network algorithm used to determined the PV output during short time
• ---

Photovoltaic panels: A review of the cooling techniques (2016)^[50]

• This paper studied the different cooling techniques of PV module and discusses its effectiveness compering the process and overall net efficiency.
• The author has taken into consideration different cooling techniques like passive cooling, active cooling, thermal electric cooling, heat pipe cooling and Nano fluid cooling.
• A comparison among the different techniques was made taking the maximum power gain into account and dividing it with effective surface of PV cell. The comparison was plotted in a graph between cooling technique and maximum peak power gain per square unit.
• Taking into account different criteria's active cooling technique have higher efficiency.
• ---

Increased electrical yield via water flow over the front of photovoltaic panels(2004)^[51]

• The paper discusses about cutting optical losses by use of water(refractive index 1.3), keeping the surface clean and decreasing the cell temperature.
• How the solar radiation hitting at a certain angle increases the reflection losses which can account for 8-15% loss in a day for conventional PV system under STC. It also explains how a material like water can compensate the reflection loss providing a better refractive index of 1.3.
• It also discusses about the thermal losses associated with PV module and how by controlling the temperature of the PV module the efficiency can be increased . Flow of water on the module front absorbs the heat and brings down the temperature of the module.
• The set up was tested for two modules, one with cooling technique and other without that. The graph has been plotted which gives a clear picture how the module with cooling technique maintained a temperature much below the temperature of the module without cooling, thus giving better efficiency.
• ---

Water Cooling Method to Improve the Performance of Field-Mounted, Insulated, and Concentrating Photovoltaic Modules(2014)^[52]

• This paper discusses about how the efficiency of the PV Module is effected due to temperature, soiling. Due to soiling the amount of solar irradiance that reaches the PV module material is blocked. Higher temperature also accelerates the material and Mechanical degradation of the panel over the lifetime.
• How the flow of water acts as a cooling agent,cleaning agent reducing the panel soiling and reduces the reflectance of the incoming light.
• The set up was created for two sets of panels to be tested on different parameters and techniques like cooling on open rack module, cooling test on insulated pv panels, cooling through ice water etc. Different net results in terms of efficiency was calculated and studied.
• Depending upon the energy implications, economic benefits and climatic factors different conditions and their feasibility were studied. How a control system could timeline the usage of cooling system as per the temperature reached was also suggested. which would limit the power consumptions and water evaporation and eventually give a better net efficiency.
• ---

Passive cooling technology for photovoltaic panels for domestic houses(2014)^[53]

• A rainwater-cooling system is employed to improve the efficiency of solar panels
• A schematic diagram of proposed system is presented and heat transfer on panel surface is described
• Rainwater estimation and and improvement in efficiency of the system are shown in tabular and graphical forms
• Payback period of 14 years as per paper
• ---

Photovoltaic panels: A review of the cooling techniques(2016)^[54]

• A review of major cooling techniques
• Passive cooling, active cooling, heat pipe cooling, nano fluid cooling and thermoelectric cooling techniques are described
• Active cooling has higher efficiency than passive ones
• ---

An active cooling system for photovoltaic modules(2012)^[55]

• Active cooling system explained
• Heat transfer modeling performed
• Mathematical formulations with panel engineering sketches are shown
• ---

Effect of Water Cooling on the Energy Conversion Efficiency of PV Cell(2016)^[56]

• The focus of this paper is to study the effects of water cooling of the panel on its efficiency and to compare that with efficiency of panel without cooling.
• The mathematical equations for efficiency relating different parameters with cooling and non-cooling technique has been defined.
• A graph has been plotted between peak efficiency and mass flow rate of water(liter/hr.) and it has been observed that flow rate above 2 liter/hr. drags down the peak efficiency of the panel.
• Different graphs has been plotted for Times in hour Vs Solar panel temperature Vs Power output Vs Output efficiency and it is clear that the panel with cooling technology yields a better performance.
• ---

Indoor Test Performance of PV Panel through Water Cooling Method(2015)^[57]

• The aim of this paper is to study how to increase the electrical efficiency of PV Pnael. It depends on environmental factors like solar radiation and operating temperature.
• The arrangement with halogen bulb for solar radiation, dc water pump for spraying water and 50M mono crystalline PV panel is described along with different measuring devices for measurement of solar radiation and performance of PV panels.
• Graph has been plotted to show the difference between the temperature by the PV panel at different solar radiation with water cooling and without water cooling.
• Graph has been plotted to show the difference in maximum voltage output, maximum current output and maximum power output with respect to different solar radiation with and without water cooling technique and their results has been compared.
• ---

Water spray cooling technique applied on a photovoltaic panel: The performance response(2016)^[58]

• THe purpose of this paper is to study a water spraying technique, implemented on both sides of PV panel to gain an optimal cooling technique and compare it with other cooling circumtances.
• A mathematical equations for calculating the heat loss is introduced taking into consideration the panel front and back temperature.
• Different graphs have been plotted with different cooling process a)Front cooling b) Back cooling c)Both sides simultaneously. various graphs of voltage, current and power output has been plotted and studied varying the different process above.

Simulation of PV System

• ---

Comparison of PV system performance model with measured PV system performance(2008)^[59]

• Performance-model in SAM is compared with performance of physical measurement of PV system
• LCOE (Levelized Cost of Energy) is key performance indicator according to Department of Solar Energy Technology Program
• LCOE lifecycle cost, installed cost, performance, operating costs, maintenance costs with reliability included
• Test case at Sandia with grid-tied PV system with 3 systems with tilt along the latitude such that no shading is observed
• Modeling performed for Raiations, module performance and invertor
• Performance submodels—radiation, performance of module and invertor—under Solar Advisor Model gave reasonable agreement. Error noted for various model lies within ±1 to ±3%
• Non-crystalline technologies showed variations between models studied
• Use of derate factors—such as shading and wiring losses—are important factors during simulation and comparison studies
• ---

Modeling Photovoltaic and Concentrating Solar Power Trough Performance, Cost, and Financing with the Solar Advisor Model(2008)^[60]

• Built System Advisor Model(SAM) by the staff of NREL and Sandia National Laboratory to support the professionals of solar industry doing reserch in solar
• SAM is used to compare different solar technology on the same platform from the point of view of performance, cost and economic aspects
• Having user friendly GUI interface so anybody can use it effectively
• SAM has some readily available models for different pv modulesand for inverters to compare the performance
• ---

WREF 2012: P50/P90 ANALYSIS FOR SOLAR ENERGY SYSTEMS USING THE SYSTEM ADVISOR MODEL(2012)^[61]

Abstract: Before installing a solar power plant the financial risk associated with has to be analyzed. There are different methodology used for this purpose and in this paper two metodology used by NREL is described.

• Data without describing the major event for the particular location can be found from Typical Meteorological Year data sets, which are used for preliminary research
• More detailed analysis for solar radiation and weather data are available at National Solar Radiation Database(NSRDB) and National Climatic Data Center(NCDC)
• In 50 method the possibilities of power output greater than 50% of the preset value is 50% and silmilar in P90 method it is greater than 90%
• ---

PV system model reduction for reliability assessment studies(2013)^[62]

• Analyzed the reliability of solar photovoltaic energy in modern power systems
• Performed simulations for the modeled pv systems for eight different locations
• Proposed model reduces the data required for PV system comparison , yet gives the accurate results
• ---

Design Parameters of 10kW Floating Solar Power Plant(2015)^[63]

• The paper describes the importance and advantages of floating solar power plant
• Reduction of evaporation (70%) and algal bloom, viable in parts of India where land acquisition is problem
• Parts of the system: solar PV module, string inverter, module mounting structure, cable and connectors, FRP floating platform, mooring arrangement, access gangway and electrical installations
• Few challenges such as to withstand wind speed, water current speed, snow load and corrosion due to water moisture
• Drawback : such investment is 1.2 times conventional land solar installations
• ---

Water canal use for the implementation and efficiency optimization of photovoltaic facilities: Tajo-Segura transfer scenario(2016)^[64]

• The pilot project at Narmada Canal, Gujarat for 1 MW is described
• A canal top approaches in PV system is explained
• The advantages of canal top installation for Tajo-Segura canal in Spain is demostrrated
• The savings and pay back is also obtained
• A sectionalized study of canal is performed
• Shading effects are also studied and the cooling techniques is also shown with improvements in temperature of the solar panels contributing towards better efficiency
• ---

A survey on floating solar power(2016)^[65]

• Explains need of floating solar system and feasibility of solar power in India with almost 300 days of sunshine
• HDPE (High Density Poly Ethylene) with cheaper cost and reliability is proposed choice for installation
• HDPE structure is shown with schematic diagram in the paper
• Describes installation at Far Niente Winery in Napa California (SPG)
• Describes installation at Kolkata commissioned by VikramSolar and Arka College
• ---

Canal Top Solar Energy Harvesting using Reflector(2016)^[66]

• Water savings estimation is shown with a simple equation
• Canal top PV with reflectors is presented with shadow effects and tilt angles
• Expression for reflector orientation is presented
• ---

Incorporation of NREL Solar Advisor Model Photovoltaic Capabilities with GridLAB-D(2012)^[67]

• Various algorithms namely: SOLPAS, Perez Tilt Model, Flat Plate Efficiency Model are presented
• Comparative analysis for GridLAB-D model and SAM model shows similar results
• Proposed in studies: GridLAB-D can model a distributed generation system more accurately

Comparison of PV System for land and water body

• ---

Study on electrical power output of floating photovoltaic and conventional photovoltaic(2013)^[68]

• Best PV module's performance is claimed to be observed at ambient temperature of 25 degree celsius with irradiation of 1000W/sq.m.
• Study is conducted in Malaysia where the temperature is observed 30 degree celsius during the day time.
• Efficiency of PV cells decrease when subjected to highly intensive solar radiation.
• Heat sink should be chosen based on thermal conductivity value, material density and cost.
• Higher electrical power output is observed with floating photovoltaic module than the conventional module.

Study on performance of 80 watt floating photovoltaic panel(2014)^[69]

• The efficiency reduces by 0.485% per 1 degree C increase in temperature
• Use of PVC pipe and Al as floating structure due to their light weight and thermal conductivity respectively
• Tilt angle needs to be between 0 to 7 degrees for Peninsular Malaysia
• Proposed for places with one season throughout the year
• Temperature difference for foalting and overland installation is compared
• Energy gain difference between both types is compared showing superior performance of floating PV
• Power gain increased by 15.5% for floating PV under this study
• ---

A Study on Power Generation Analysis of Floating PV System Considering Environmental Impact(2014)^[70]

• Performance Analysis of Hapcheon 100 and 500kW floating solar PV is presented over the months of the year
• On the basis of average generation, floating plant is expensive than overland plant
• Juam 2.4kW floating Vs overland PV system superior performance of floating installation
• Effect of wind speed with change in orientation and location (due to movement) is studied for Juam floating solar PV.
• Generating efficiency for floating installation is 11% higher than overland installations by ignoring the effects of wind.
• ---

A study of floating PV Module Efficiency(2014)^[71]

• Experiments are conducted in a place (Maltese islands) with higher irradiation and the ratio of water to land area is 10:1.
• Different setups are compared such as solar panels on land, panels on floating water and panels on sea water with salt accumulated on it.
• Water cooled setup performed better than the non-water cooled system by a factor of 9.6% in summer and by 3% in winter.
• Sea salt accumulated system produced 3.8% greater energy output than the ground reflected system.
• As it is more costlier to deploy solar panels on water than on the land, the power produced per square meter of the material used is of greater importance ad it is high for crystalline cells.
• On the whole energy efficiency is always high for a floating panel than the terrestrial one.
• ---

Design and installation of floating type photovoltaic energy generation system using FRP members(2014)^[72]

• This design is installed and tested at the sea site in Korea.
• Tracking type floating PV model.
• Temperature of the PV panels in the floating type PV energy generation system is lower than the land type due to relatively low temperature of the sea site.
• Light weight materials such as pultruded FRP (Fiber Reinforced Polymer) are used in the floating structure.
• FRP is highly resistant to corrosion.
• The link system installed between the unit modules is made of PFRP, recycled used tire, and olyethylene synthetic fiber rope.
• Finite element analysis of the PV system is conducted based on the mechanical properties of the PFRP (Fiber reinforced Polymeric Plastic).
• Floating model reduces the disadvantages such as environmental disruption and high cost of land use that are incurred by the PV land system.
• ---

The thin film flexible floating PV (T3F-PV) array: The concept and development of the prototype (2014)^[73]

• World's first deployment of a floating thin film PV – small prototype in Subdury,Canada.
• Accumulation of dirt on the panels result in the reduction of output efficiency by 1%.
• Proposed to develop a larger scale prototype.
• Component cost of the floating PV array prototype is tabulated.
• Since this is the first project PV installation costs are high and the design needs modifications.
• Design changes are recommended that are suitable for operation in harsher environments(wave forces)
• ---

Variability of Power from Large Scale Solar Photostatic Scenarios in the State of Gujarat(2014)^[74]

• Data of Global Horizontal Iradiance and Direct Normal Irradiance had dereived from the satelite images of the Meteoset satelite for 10 km*10 km area
• Applied sub-hour irradiance algorithm(SIA) for down scaling hourly data to one minute time interval
• Gujarat has solar power output of around 5.5-6 kwh/square meter/day and the results of this paper will help to find the optimal location in the state
• Five potential locations selected for the for the future expansion scenario
• This studies helps to integrate solar power with the conventional energy sources to meet the load demand and other challenges.
• ---

Empirical Research on the efficiency of Floating PV systems compared with Overland PV Systems(2013)^[75]

• 100kW and 500kW floating PV systems are installed on water body in Korea. Utility of both installations compared with overland PV (1MW) systems.
• Capacity Factor is calculated to determine the generation quantity.
• Daily average generation quantity of overland PV system is compared with the Daily average generation capacity of floating PV system.
• Coefficient of utilization – 13.5% higher for floating PV compared to land PV.
• Generating efficiency – floating PV is superior by 11%

H2O saving simulation

• ---

Evaporation Reduction by Suspended and Floating Covers: Overview, Modelling and Efficiency(2010)^[76]

• Design for Australia's South East Queensland which has heavy pressure of water demand
• Use of suspended covers and floating covers, types of covers are discussed
• Highest efficiency for SuperSpan covers together with greater life
• Evaporation rate expression used for modeling the evaporation
• Cost comparison shows cost per KL water for SuperSpan ranks second (after AquaCap)
• 2D model is presented and 3D model is proposed for future research work
• ---

Design and analysis of a canal section for minimum water loss(2011)^[77]

• Seepage and evaporation water losses are discussed for water canals
• Objective function is water loss and its minimization is the task presented in this paper
• Both evaporation and seepage functions are defined
• The Lagrange multipliers are used to find out the optimal size of the canal such that evaporation losses are minimum
• ---

Evaluating Potential for floating solar installations on Arizona Water Management(2016)^[78]

• Study highlights the need of foatovolatics and terms it as "drought adaptation technology"
• Water loss through Central Arizona Project is around 4.4% equating to 58,921,434 gallons per day
• Reduction of carcinogenic content in water due to lowering exposure to sunlight for bromate formation from chlorine and bromine
• NREL estimation ignores transmission infrastructure and other costs and reliability
• Various deigns of floating installations are discussed
• Savings in water are evaluated using an empirical formula
• A pilot location is proposed at lake Pleasant Reservoir
• Cost per watt is $1.36 including the advantage of government subsidy
• ---

A new photovoltaic floating cover system for water reservoirs(2013)^[79]

• Design in this paper is suitable to agricultural reservoirs where there are no heavy wave forces and is implemented in Spain.
• Water losses by evaporation in farms amounted to 17 percent in Spain.
• Floating cover systems require site specific planning and design to be successful.
• Floating modules joined by means of pins cover the water surface in this design.
• Elastic joints are used to easily adapt to varying reservoir water levels.
• Evaporation reduction achieved through cooling/floating photovoltaic system is around 80%.
• ---

Determination of evaporation and seepage losses, Upper Lake Mary near Flagstaff, Arizona(1998)^[80]

• Types of losses due to seepage and evaporation are discussed
• Evaporation estimation using mass-transfer with several modified expressions
• Estimates of mean annual and mean monthly evaporation were obtained
• Equation 5 in the paper gives most accuracy in results
• ---

Water losses in canal networking (Narmada canal section near Gandhinagar-Ahmedabad)(2016)^[81]

• Seepage and evaporation losses for Narmada canal section is shown
• Briefly explains sections/phases in Narmada Canal
• Inflow-outflow method to calculate seepage losses is presented
• Drawbacks of Narmada canal is discussed: Algal formation and public pollution
• ---

Floating solar photovoltaic systems: An overview and their feasibility at Kota in Rajasthan^[82]

• Floating PV technology is discussed in this paper.
• Advantages and components of FPV has been dsiscussed.
• FPV Installations in India have been discussed.
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Potential of floating photovoltaic system for energy generation and reduction of water evaporation at four different lakes in Rajasthan^[83]====

• Detailed description on FPV, its advantages are discussed.
• For study of FPV, four lakes of Rajasthan, India are considered.
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Methods for the quantification of evaporation from lakes (prepared for the World Meteorological Organization's Commission for Hydrology)(2008)^[84]

• A brief summary of methods described:

Method	Advantages	Limitation
Mass-balance method	doesn't require surface temperature for calculation	difficult/expensive to measure all elements
Bulk-transfer method	makes use of data easily available	sensitivity to vapor pressure and difficulty in wind function definition
Energy balance method	gives most accurate results with thermal stratification taken into account
Equilibrium temperature method	relatively new, uses heat storage of water and metro logical data into account	doesn't include thermal stratification

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Estimating evaporation based on standard meteorological data – progress since 2007(2014)^[85]

• Most recent methods of estimating evaporation is summarized (since 2007 to 2014)
• Review of remote sensing enhancing the application of standard procedures of estimating evaporation
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Lake Evaporation in a Hyper-Arid Environment, Northwest of China—Measurement and Estimation(2016)^[86]

• Study performed for East Juyan Lake, China
• An evaporation model is derived and its validation can be done with known data or from pan evaporation tests
• Floating pan evaporation techniques and its sensitivity analysis is presented
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Floating photovoltaic plants: Performance analysis and design solutions^[87]

• Limitations of further development of PV installations are described.
• Advantages of PV floating solutions.
• Supporting structures of FPV are described.
• Cooling and cleaning in FPV is described.

Economics of PV on water body and sensitivity analysis

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Assumptions and the Levelized Cost of Energy for Photovoltaics(2011)^[88]

• LCOE is defined and explained in detail about its use in cost analysis of solar PV installations
• SunPower simplified LCOE expression is cited
• SAM presents LCOE as real and nominal (expressions are shown with required revenues over life of the project)
• Single value of LCOE doesn't include effects of economic and financial aspects of project
• Monte Carlo simulation provides much clear projection of LCOE with single inputs, with its few advantages: probabilistic results, sensitivity analysis and co-relation of inputs
• Three locations Sacramento, Chicago and Boston with 20MW installation are compared for LCOE estimations
• Major assumptions for two main parts of LCOE namely: cost and energy production are presented
• Sensitivity analysis for three places with input parameters is presented showing real discount rate has greater impact
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Floatovoltaics: Quantifying the Benefits of a Hydro-Solar Power Fusion(2013)^[89]

• Pairing of water and solar could increase production efficiency by 8-10% through panel cooling and save millions of litres of water from evaporation.
• A Floatovoltaic system is feasible only when the benefits of the project such as water saved from cooling and reduced evaporation plus the increase in power output outweigh the floating costs.
• Shading water with the solar arrays can reduce the evaporation losses by 70%.
• Maximum power is linearly related to both temperature and irradiance.
• In areas with lots of irradiance and low land prices like deserts, electricity has to be transported long distances to reach users.
• 6% of United States electrical energy is lost during transmission and distribution.
• Connecting a solar array to the existing power grid would save on transmission infrastructure costs.
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Floating photovoltaic power plant: A review](2015)^[90]

• A nice paper which explains from all basics. Explains about different types of solar PV used in current world
• Given names of companies who have installed floating PV's worldwide and their capacity. Reviews on different types of floating installations.
• Explains only on still water bodies. In India arge water bodies are available in eastern, Sothern and South-eastern part of the country in states such as West Bengal, Assam, Orissa and Andhra Pradesh, Tamil Nadu and Kerala.
• In agriculture based country like India, it saves valuable land and reduces water evaporation by installing Floatovoltaics
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Some Remarks about the Deployment of Floating PV Systems in Brazil(2017)^[91]

• sensitivity analysis of Solar Floatovoltaics implemented in Brazil.
• Floating PV's are 11% effective than conventional one due to lower temperatures on water than on ground
• The increase in the efficiency of the floating PV plant due to evaporative cooling may be significant in the Northeast region of the country (Sobradinho reservoir), but not significant in the North region (Balbina reservoir)
• The installation of the system is also more difficult and costly. Apparently, this extra cost is offset by the fact that the system does not use and, which results in a cost reduction
• Large scale floating PV plants can have a significant environmental impact by reducing algae growth and water oxygenation, and to minimize the first effect, glass-glass photovoltaic modules shall be used in Brazil
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Theoretical and experimental analysis of a floating photovoltaic cover for water irrigation reservoirs (2014)^[92]

• A prototype of 20kWp was implemented for water irrigation reservoirs (Spain).
• Focuses on the theoretical and experimental analysis of a floating photovoltaic cover system for water irrigation reservoirs.
• Shielding of water with floating materials obstruct photosynthesis, reduce algae growth and thus improves water quality.
• Lower tilt angles provide better electrical performance.
• Significant saving of Co2 is observed.
• PV electricity generation costs for a kWh are expressed in profitability ratio.
• Analysis states that the plant has a nominal capacity of 300kWp, gives annual production of 425000 kWh/year of renewable energy.
• Savings in water is observed to be 5000 cubic meter or 25% of the reservoir's storage capacity.
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A Review on new era of solar power systems: Floatovoltaic systems or Floating solar power plants (2015)^[93]

• Due to the cooling effects of water, its floating PV systems generate about 10 percent more electricity than rooftop or ground-mounted systems of the same size.
• HDPE is commonly used because of its high density polyethylene structure. Can be installed in drinking water tanks. It is resistant to UV. Can withstand winds up to 118 mph. Costs less per module compared to LUPOLEN 5261Z, and Zinc coated stainless steel structures.
• In this paper, they have considered different types of PV cells. Concluded that efficiency depends on area and cost of installation depends on the area considering transporation and manufacturing.
• It takes as less as a week to install 200kW power plant with 800 floating panels in any given space.
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A study on major design elements of tracking - type floating photovoltaic systems (2014)^[94]

• Tracking-type floating PV system is explained and compared with fixed-type. Fixed-type has the angle of PV module is fixed at a certain angle and tracking-type where the azimuth and altitude of the sun is tracked to receive the sunlight perpendicular to the module surface.
• On ground dual-axis tracking-type is 30% greater than a fixed-type. These are useful in countries like Korea to utilize the limited resources to the maximum.
• Design is little bit different from normal floatovoltaic. Design is explained in this paper.
• A tracking algorithm is provided for efficient use of PV. An error can be occurred due to external disturbing factors. A error correction method can be followed using GPS receiver and terrestrial magnetism sensor.
• Various rotation mechanisms like rope and forward/reverse rotation method, worm and worm gear method, chain and roller guide method, fixed buoyancy roller guide method and chain or rope, and gear and rotation ring methods can be used to maintain internal rotating structure.
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Uninterrupted Green Power using Floating Solar PV with Pumped Hydro Energy Storage & Hydroelectric in India (2016)^[95]

• This paper aims at combining FSPV(Floating Solar PV) with PHES(Pumped Hydro Energy Storage) & Hydroelectric to try & create a model for a source of Uninterrupted Green Power. It attempts to estimate the potential of this model in large reservoirs in India.
• The basic technology for both FSPV & PHES is well established & functioning successfully in many countries. But a combination of the same with hydroelectric to meet the requirement of Uninterrupted Green Power for the Indian consumer is the need of the hour.
• This way renewable energy can be produced efficiently. This combination will result (in one of the configurations considered) at an initial cost of USD$1715.83 per kW installed and a cost of energy of USD$ 0.059/kWh.
• saves the utilization of precious land resource of minimum 4 acres per MWp needed for ground mounted solar PV. output of Solar PV modules improves due to better cooling on reservoir water surface environment.
• The existing infrastructure for power evacuation in hydroelectric power plants can be augmented & used.

Sustainability

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Analysis of the Potential for Use of Floating Photovoltaic Systems on Mine Pit Lakes: Case Study at the Ssangyong Open-Pit Limestone Mine in Korea(2016)^[96]

• Abandoned mine sites can be utilized for implementation of solar PV
• Limiting factors includes availability of smaller area with shading effects
• SAM modeling performed using weather information and proposed generation along with studies on economy showing return in 12.3 years in Koeran Mine Pit Lakes
• Annual reduction in emissions found to be 471.21tCO2/year
• Location, temperature, wind speed, irradiance level
• Using ArcGIS the feasible site was determined along with design of PV system (tilt angles, required area, PV module, inverter)
• Net present value (NPV) and Greenhouse gas reduction expressions are presented.
• Variations in output w.r.t. tilt angles
• Although, PV system installation needs 1.7 times higher expenditure than forestation of same area, but GHG emissions are reduced by half.

References