Solar floatovoltaics lit review: Difference between revisions

Introduction

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 arrrises 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.

H2O cooling function of Solar PV (Floatovoltaic)

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An active cooling system for photovoltaic modules(2010)^[1]

• 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)^[2]

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• 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

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Assessment of the Operating Temprature of Crystalline PV Modules Baesd on Real Use Conditions(2013)^[3]

• 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

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Improved Power Output of PV System by Low Cost Evaporative Cooling Technology(2013)^[4]

• 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.

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Improving of the photovoltaic / thermal system performance using water cooling technique (2014)^[5]

• 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.

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Experimental evaluation of the performance of a photovoltaic panel with water cooling(2014)^[6]

• 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.

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Increasing solar panel efficiency in a sustainable manner(2014)^[7]

• 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%.

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Study on performance enhancement of PV cells by water spray cooling for the climatic conditions of Coimbatore, Tamilnadu(2015)^[8]

• 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.

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Experimental Assessment of PV Module Cooling Strategies(2015)^[9]

• 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.

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Experimental Study on Efficiency Enhancement of PV Systems With Combined Effect of Cooling and Maximum Power Point Tracking(2016)^[10]

• 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%.

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Simulation of PV System

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Comparison of PV system performance model with measured PV system performance(2008)^[11]

• 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

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Modeling Photovoltaic and Concentrating Solar Power Trough Performance, Cost, and Financing with the Solar Advisor Model(2008)^[12]

• 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

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WREF 2012: P50/P90 ANALYSIS FOR SOLAR ENERGY SYSTEMS USING THE SYSTEM ADVISOR MODEL(2012)^[13]

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%

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PV system model reduction for reliability assessment studies(2013)^[14]

• 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

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Design Parameters of 10kW Floating Solar Power Plant(2015)^[15]

• 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

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Water canal use for the implementation and efficiency optimization of photovoltaic facilities: Tajo-Segura transfer scenario(2016)^[16]

• 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

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A survey on floating solar power(2016)^[17]

• 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

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Comparison of PV System for land and water body

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Study on electrical power output of floating photovoltaic and conventional photovoltaic(2013)^[18]

• 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)^[19]

• 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

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A Study on Power Generation Analysis of Floating PV System Considering Environmental Impact(2014)^[20]

• 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.

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A study of floating PV Module Efficiency(2014)^[21]

• 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.

H2O saving simulation

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Evaporation Reduction by Suspended and Floating Covers: Overview, Modelling and Efficiency(2010)^[22]

• 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

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Design and analysis of a canal section for minimum water loss(2011)^[23]

• 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

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Evaluating Potential for floating solar installations on Arizona Water Management(2016)^[24]

• 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

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A new photovoltaic floating cover system for water reservoirs(2013)^[25]

• 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%.

Economics of PV on water body and sensitivity analysis

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Assumptions and the Levelized Cost of Energy for Photovoltaics(2011)^[26]

• 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)^[27]

• 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)^[28]

• very nice paper from all basics. Explains about different types of solar PV
• 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. An expected imp

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Some Remarks about the Deployment of Floating PV Systems in Brazil(2017)^[29]

• 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

lementation in India is given.

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)^[30]

• 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.

Contributors

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Arpit Pravin Sreenija Surya Tanmoy

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References