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Sensitivity analysis of design parameters and power gain correlations of bi-facial solar PV system is presented in this paper. The main objectives are to study the effects of albedo, tilt angle and height from the ground on the performance of the system; determine the optimum operating conditions; and the development of new correlations for the annual energy yield and bifacial gain of bPV solar system. Three primarily significant installation parameters, albedo [10%, 50%, 90%], tilt angle [15°, 25°, 35°] and height [0.5 m, 1 m, 1.5 m] are investigated with PVSYST for bifacial and mono-facial PV modules. The response surface methodology (RSM) based optimization method is used to determine the optimum conditions and the interaction of these three parameters on the performance of bPV solar system. New quadratic equations or correlations are introduced to estimate the annual energy yield and bifacial gain of bPV. The results show that the albedo is the most significant parameter between tilt angle and height. The increase in albedo factor and height of bPV modules from ground increase the energy yield. In this study, the optimum tilt angle of bPV is found to be 35°for higher albedo and elevation of bPV from the ground as compared to 25° of mPV. An average daily bifacial gain of 35.68% can be achieved in clear sunny day with 90% albedo, tilt angle of 35° and at height of 1.5 m. The maximum specific productions of 192.4 kWh/kWp and 160.6 kWh/kWp are observed in May for bPV and mPV, respectively while the maximum bifacial gain of 21.93% is found in July.

This work presents, for the first time, a statistical model to forecast the electrical efficiency of concentrated photovoltaic-thermoelectric system (CPV-TE). The main objective of this work is to analyze the impact of the input factors (product of solar radiation and optical concentration, external load resistance, leg height of TE and ambient temperature) most affecting the electrical efficiency of CPV-TE system. An innovative and integrated approach based on a multi-physics numerical model coupling radiative, conductive and convective heat transfers Seebeck and photoelectrical conversion physical phenomena inside the CPV-TE collector and a response surface methodology (RSM) model was developed. COMSOL 5.4 Multiphysics software is used to perform the three-dimensional numerical study based on finite element method. Furthermore, results from the numerical model is then analysed using the statistical tool, response surface methodology. The analysis of variance (ANOVA) is conducted to develop the quadratic regression model and examine the statistical significance of each input factor. The results reveal that the obtained determination coefficient ( R 2 ) for electrical efficiency is 0.9945. An excellent fitting is achieved between forecast values obtained from the statistical model and the numerical data provided by the three-dimensional numerical model. The influence of the parameters in order of importance on the electrical efficiency are respectively: product of solar radiation and optical concentration, the height legs of TE, external electrical resistance load, and ambient temperature. A simple polynomial statistical model is created in this work to predict and maximize the electrical efficiency from the solar CPV-TE system based on the four investigated input parameters. The maximum electrical efficiency of the proposed CPVTE (17.448%) is obtained for optimum operating parameters at 229.698 W/m2 value of product of solar radiation and optical concentration, 303.353 K value of ambient temperature, 2.681Ω value of resistance electrical load and at 3.083 mm value of height of TE module.

Gulf countries like the UAE are blessed with plenty of sunshine over the whole year. The solar photovoltaic system is an appropriate alternative for the production of electricity. Solar irradiance is partially converted into electricity and the remaining is dissipated as accumulated heat which elevates the operating temperature of the solar PV panel. The elevated temperature has adverse effect on the electrical performance of SPV panels. In this study, a unique back cooling, through the application of waste air from a centralized air conditioning system, is presented to compensate for the degradation of electrical power by the temperature. The experimental results have shown an average reduction of 18.05 °C in the operating temperature of the examined monocrystalline solar panel, which improves the generated electrical power by 8.65 % . In a typical clear day of July, an improvement of 0.97 % in the electrical efficiency of the SPV panel has been achieved through the proposed cooling strategy. The electrical energy produced by the cooled SPV panel is 677.89 Wh / day , as compared to 623.90 Wh / day of the reference panel. The results have justified the viability of waste air from the air conditioning system as a novel application of back cooling of SPV panels. The IR thermography is also employed to study the distribution of temperature and the estimation of the performance of SPV panels, along with the detection of the superficial defects. In the end, a new correlation is developed to accurately estimate the output power of the PV panel through IR measured temperature.

This work proposes an innovative statistical model by utilizing the response surface methodology (RSM) method to analyze a batch solar behaviour still. This investigation's main goal is to study the impact of the input factors (solar radiation, ambient temperature, water depth, and thickness of insulation) most influencing water productivity. The polynomial regression model derived from a numerical balance energy model to predict the solar's productivity still is established. The quadratic model is checked by a coefficient of determination (R2). An excellent fitting is attained between the forecasted results derived from the statistical model and the numerical simulation derived from the heat balance model. The results reveal that the importance of the influence in the order of impact on the amount of distilled water is water depth, solar radiation, ambient temperature, and thickness of insulation. A simple polynomial statistical model is stated in this investigation to determine and maximize the amount of distilled water from solar still based on the four considered input factors.

The performance of solar air conditioning system (SACS) using Lithium-Bromide/water (Li–Br/H2O) solution and nanofluid -based parabolic trough collectors (PTC) under hot and humid climate conditions is presented in this study. The main objectives are to investigate the effects of different types of nanofluid (Al2O3/H2O and Cu/H2O) and the concentration of nanoparticle Cu (0.2 and 0.5 wt %) on the coefficient of performance (COP) of SACS system during a winter and summer days in desert regions. Mathematical models of the SACS system including the solar PTC, tank storage and the single-effect Li–Br/H2O absorption chiller are developed. The numerical simulation results show a good agreement with the experiment data accessible in literature. The results show that Cu/H2O nanofluid has the best performance. For the cold day and at noontime, the COP for pure water, 0.5 vol% Al2O3/H2O nanofluid and 0.5 vol% Cu/H2O nanofluid are 0.64, 0.68, and 0.74, respectively. The COP during the cold day increases by 12.5% and 15.5% when the concentration of Cu nanoparticle is 0.2 %vol and 0.5 %vol respectively. For the hot day and between 9:00 a.m. to 3:00 p.m. the maximum COP obtained is 0.77, and the effect of nanofluids is negligible. The single LiBr–H2O air absorption system reaches its maximum operation. A double effect of LiBr–H2O air absorption is needed to improve the performance of the system. Keywords: Solar, Absorption chiller, Li–Br/H2O, Single effect nanofluid

The main objective of this study is to develop a novel photovoltaic thermal collector (PVT) to improve the electrical and thermal efficiencies of the solar collector. The goal is to maximize the electrical power and minimize the thermal losses of the solar panel. A novel photovoltaic thermal collector is designed and tested. The new PVT collector includes: (1) An optical anti-reflective and low-emissivity coating to reduce the radiation losses; (2) A thermal resistance to reduce the conduction losses between the photovoltaic and absorber plate; and (3) A channel heat exchanger to decrease the thermal losses between the solar cells and the cooling fluid. A transient two-dimension multi-physics model for the PVT sheet-tube and the advanced PVT collector is developed. The state variable variations are predicted by the finite volume method. A comparison between the two considered hybrid collectors in terms of thermal and electrical efficiencies and temperature distribution is performed. Moreover, the impact of arrangement (anti-reflective and low-emissivity coating, thermal resistance between the absorber plate and the cooling fluid, enhanced exchange surface area between the flat plat exchanger and the cooling fluid) on the new PVT collector is studied and analyzed. The simulation results showed clearly the advantages of using this evolution of the PVT collector compared to the basic one. Indeed, this new PVT configuration represents a series of improvements that lead to a lower PV module and higher fluid operating temperatures. Higher electrical and thermal efficiencies for the proposed PVT (15.4%, 73%) are obtained compared to the basic PVT collector (13.7%, 58%), respectively under no loss and standard test conditions.

In the present study, an experimental setup for a PVT system is designed and fabricated to investigate the economic and environmental aspects of using different nano-oxides/water fluids. Selected coolant fluids are: pure water, ZnO/water, Al2O3/water and TiO2/water nanofluids. To make nanofluids, nanoparticles are dispersed in distilled water by 0.2% weight fractions (wt%), separately. Based on the experimental results the amount of annual emission reduction and cost saving are investigated for different coolants. Furthermore, the payback period of the PVTs is compared with that of a conventional PV unit. The results are presented in five different scenarios due to increasing of the electricity price, up to the final price and the government subsidies for the renewable energy sources (1st: 10% annual price increasing, with no subsidy, 2nd: linear increasing price, with no subsidy, 3rd: 10% the annual price increasing, 50% subsidy, 4th: linear price increasing, 50% subsidy and 5th: linear price increasing, 75% subsidy). From the energy viewpoint, by using pure water, PVT/TiO2, PVT/ZnO and PVT/Al2O3, the size reduction of the PVT system in comparison with that of the PV is 21, 32, 33 and 24%, respectively, and from the exergy viewpoint these values are about 5, 6, 7, 6%, respectively.

The main objective of this study is to assess the performance of solar Llthlum-Bromlde-H 2 O absorption air conditioning system for a conference hall under hot climate conditions. The goal is to replace conventional air condition system with compressor cycle consuming high electrical power with solar based absorption chiller (increase the integration renewable resources in the energy mix, and reduce the electrical power consumption and the greenhouse gas emissions). Modeling and simulation analysis was used in this study to calculate the cooling loads of the hall; test the daily performance of the solar absorption air conditioning unit; and determine the conditions to achieve and maintain cooling conditions (temperature and humidity) to meet the requirement of the conditioned space. The results show the maximum cooling load of the hall (total floor area is 280 m2) for the month of July in Sharjah is 52 kW, the maximum useful energy gained by the parabolic trough collector PTC is 79 kW (total area of the PTC is 133 m2 and the thermal efficiency of the PTC collector is 72%), and the average coefficient of performance of solar absorption system is 67%.

Modeling and Simulation analysis is performed in this study to investigate the thermal and electrical performance of a hybrid solar photovoltaic thermal (PVT) heat pipe. This investigation was performed for the first time under hot climate conditions. Mathematical models were developed for both the thermal energy as well as the electrical energy of the solar collector. The numerical results were validated with existing experimental data available in the literature. The numerical results compare well with the experimental data. The monthly thermal and electrical energies generated by the solar collector under Sharjah weather conditions were determined and analyzed. The results obtained in the course of this study show that the integration of heat pipes with solar PV (Solar PV/Thermal) collector offers better electrical power production compared to the classical solar PV module. The maximum monthly electric electrical energy output PV/T heat pipe and classical PV module were respectively, 116 kWh and 102 kWh. However, the maximum monthly thermal generated by the PVT heat is 400 kWh.

Thermoelectric modules are capable of converting heat into electric energy via the Seebeck effect. Therefore the addition of the thermoelectric generator modules (TEG) between the PV module and the absorber plate inside a concentrated photovoltaic thermal (CPVT) solar collector can be a feasible way for to enhance their electrical generation. A comparison between the CPVT only system and CPVT system integrated with TEG (CPVT-TE) is conducted using numerical simulation. Therefore CPVT-TE with water and CPVT-TE with 0.5% graphene/water nanofluid is investigated. A transient study using the finite volume method is presented, and computation is performed for all the considered solar systems for a typical sunny day and cloudy day under London climatic conditions. The CPV and the outlet fluid temperatures, as well as, the energy and exergy calculations are carried out to assess the performance of all the considered solar systems. The results reveal that the improvements in the total electrical power generated by the CPVT-TE with 0.5% graphene/water nanofluid and CPVT-TE compared to CPVT collector are 11.15% and 9.77%, respectively for the summer day, while, that for the winter day is 5.14% and 4.58%, respectively. The reductions in the thermal power provided by the CPVT-TE with 0.5% graphene/water nanofluid and CPVT-TE compared to CPVT collector are 6% and 11.76%, for the summer day, while, that for the winter day are 4.86% and 10.53%, respectively. Moreover, the total exergies generated by 0.5% graphene/water nanofluid CPVT-TE and water CPVT-TE collectors increased by 4.88% and 0.68% respectively, for the summer day, while that for the winter day are 2.99% and 0.95% respectively, in comparison with the conventional CPVT system.

In the high concentrator photovoltaic (HCPV) systems with solar concentration ratios up to 2000 Suns, significant heat is generated in the used solar cell layer. This high generated heat requires an efficient and smart cooling technique to keep it operating at a safe operating temperature. In this paper, another ultra-high concentrator photovoltaic (UHCPV) system with a smaller cell area of 1 mm2 operating at a high solar concentration ratio (CR) up to 10,000 Suns is proposed. This smaller area requires a simple passive cooling technique even at high CR. The optimal dimensions of a passive cooling method using heat spreader are defined. A 3D thermal model for the multijunction solar cell with the heat spreader coupled with the multi-objective genetic optimization algorithm is used to define the optimal heat spreader dimensions . The model is validated with the results in the literature. The model is used to estimate the cell temperature generated electric power, and cell efficiency at different wind speed, ambient temperature, solar radiation, heat spreader length, thickness, and CR. The heat spreader dimensions were optimized for CR = 6000 suns, the optimal thickness and length were 2 mm and a of 47.5 mm, respectively. These dimensions are enough for the safe operation of the UHCPV at CR of 6000 Suns. As a case study, for a UHCPV module with a total number of cells of 10 by 10, the generated power is around 319 W at CR of 10,000 Suns. At the same condition, the monocrystalline silicon solar cell in the PERSEID SOLAR company can generate a maximum power of 144.9 W/m2. For the same area, for the UHCPV module, the generated electric power is around 319 W for 1 m2 of the module. Therefore, around 120% increase in the power can be accomplished with the use of the UHCPV module. In the UHCPV module, the total area of the cell is around 1 cm by 1 cm. Therefore, the module cost could be very low.

In this paper, an experimental and numerical study is performed to evaluate the performance of a photovoltaic thermal (PV/T) nanofluid based collector. A two-dimensional numerical model is established to study the effects of using nanofluids as working fluid in PV/T collector. The model is validated experimentally by comparing the simulations with the experimental results. The influence of concentration (0.1, 0.2 and 0.4 wt.%), types of nanoparticles (Al2O3 and Cu) and different base fluids (pure water and ethylene glycol) on the electrical and thermal performance of the collector is investigated. Also, the model is applied to predict the annual electrical and thermal output of the PV/T for three different cities: Lyon (France), Mashhad (Iran) and Monastir (Tunisia). The results indicated that using pure water as a base fluid provides a higher performance in comparison with ethylene glycol. Using Cu/water gives the best thermal and electrical efficiency in comparison to Cu/ethylene glycol, Al2O3/water and Al2O3/ethylene glycol. It is also found that the thermal and electrical energy output for Monastir (Tunisia) climate condition is higher than that of Mashhad (Iran) and Lyon (France).

Cooling PV cells is an important requirement to prevent any loss performance of PV cell and any reduction of their lifespan. Therefore, using nanofluid as working fluid in a PVT collector has become attractive due to the significant improvement in heat transfer properties as compared to conventional fluids. For the first time, this work introduces a novel statistical model by applying the response surface methodology (RSM) method to examine the electrical and thermal efficiencies of behavior of a nanofluid photovoltaic thermal (PVT) collector. The developed statistical model correlates the efficiencies of the solar collector with the operational parameters, including the heat transfer coefficient by conduction between the PV module and the absorber plate, the mass flow rate, the concentration of Zinc oxide (ZnO) nanoparticles and the tubes number. An excellent correlation is achieved between the foretold results derived from the statistical model and numerical simulation of the heat transfer model. The coefficient of determination (R2) for thermal and electrical efficiencies are 0.9888 and 0.9908, respectively. The outcomes show that the heat transfer coefficient by conduction between the PV and the absorber, the mass flow rate are notable factors compared to concentration of ZnO nanoparticles and the tube number.

The photovoltaic thermal collector can provide thermal and heat power at the same time. In this paper, a photovoltaic/thermal sheet and tube collector has been numerically investigated. The paper focuses on the development of a hybrid solar collector PV/T. This model will be applied to optimize the operation of the PVT collector in the semi-arid climate. A mathematical model has been developed to determine the dynamic behavior of the collector, based on the energy balance of six main components namely a transparent cover, a PV module, a plate absorber, a tube, water in the tube and insulation. It has been validated by comparing the obtained simulation results with experimental results available in literature, where good agreement has been noted. Using our developed model, the heat and electrical power of sheet and tube collector has been analyzed for four typical days of year with the meteorological parameters of Monastir, Tunisia. Furthermore, the effect of solar radiation, the inlet water temperature, the number of glazing covers and the conductive heat transfer coefficient between plate absorber and PV module have been involved to identify their influence on the thermal and electrical efficiencies. The monthly thermal and electrical energies is also evaluated.

PV/T solar collector is an energy system designed to provide both thermal and electrical energies at the same time. In this paper, the dynamic simulation of a photovoltaic thermal collector is presented. The effect of different parameters, such as meteorological, design and optical parameters are investigated. Furthermore, evaluation and comparative economic analyses among different designs of PV/T sheet-tube collectors, conventional thermal solar collector and PV module is conducted under Monastir (Tunisia) climatic conditions. Numerical results show that the thermal and electrical efficiencies significantly depend on the studied parameters. It is also found that, in terms of economy, the uncovered PV/T collector yield the best performance among others.