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Abstract

The study aimed at revealing the techno-economic analyses of the temperature management of photovoltaic (PV) modules. For this aim, an existing PV power plant (PP) located in Zanjan, north-west of Iran was analyzed experimentally. Two different cooling scenarios (cases A and B with 3 and 6 low-energy fans per module) were considered. The net energy balance showed that more net electrical energy is produced in case A. The net specific energy (kWh per kWp) could be increased up to 4.4% and 4.1% in July, respectively for cases A and B. The selected cooling system (i.e. case A) was analyzed economically according to three different possible scenarios: considering different feed-in tariff (FiT) rates, change in PV module degradation rates, and increasing the size of a PV PP vs applying the thermal management system. Results revealed that a thermal management system would be economically justifiable only at high FiT rates. Finally, considering the reduction in the degradation rate of PV modules is necessary for economic analyses due to the possible lowering in the pay-back period as up to three years seen in the present study.

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... The curved shape is also used in silos, biogas tanks, greenhouses and structures. The Taguchi factorial experiment and response surface methods are used to improve the precision of the test and reduce the expense of testing and speed up the experiment [27]. Conventional solar panels involve the construction of glass panels that are usually not quite consistent with cylindrical geometric shapes [28]. ...
... Although sources [12,13] claimed the optimum performance of the photovoltaic system at 1000 W/m 2 , our study and [18,22,24] found that the ideal range for energy generation is consequently 800 W/m 2 in flexible photovoltaic systems. Economically, the current research system was estimated to cost USD 0.8 per watt, which is more costly than in other studies [26,27,29]. A reason for this is that equipment for gluing and mounting solar panels on cylindrical and hemispherical surfaces was used. ...
... Electrical performance of 7.30% and 7.15% was recorded in these trials, respectively. The payback time varies by nation; in this research, it was computed at a flat rate of 8.25 years, although in other studies, it is often reported in the range of 3-5 years [4,15,27]. The pareto analysis introduces variables that affect system performance, but it is recommended to conduct on-site analysis of similar systems and compare the results during seasonal periods. ...
Article
Renewable energy policies emphasize both the utilization of renewable energy sources and the improvement of energy efficiency. Over the past decade, built-in photovoltaic (BIPV) technolo-gies have mostly focused on using photovoltaic ideas and have been shown to aid buildings that partially meet their load as sustainable solar energy generating technologies. It is challenging to install conventional photovoltaic systems on curved facades. In this research, elastic solar panels assisted by flexible photovoltaic systems (FPVs) were developed, fabricated, and analyzed on a 1 m2 scale. A flexible structure on a flat, hemispherical, and cylindrical substrate was studied in real terms. Using the LabVIEW application, warm and dry climate data has been recognized and transmitted online. The results showed that when installed on the silo and biogas interfaces, the fill factor was 88% and 84%, respectively. Annual energy production on the flat surface was 810 kWh, on the cylindrical surface was 960 kWh, and on the hemisphere surface was 1000 kWh, re-spectively. The economic results indicate that the net present value (NPV) at a flat surface is USD 697.52, with an internal rate of return (IRR) of 34.81% and a capital return term of 8.58 years. Cy-lindrical surfaces and hemispheres each see an increase of USD 955.18. The investment yield re-turned 39.29% and 40.47% for cylindrical and hemispheres structures. A 20% increase in fixed investment in the flat system increased IRR by 21.3%, while this increase was 25.59% in the cy-lindrical system and 24.58% in the hemisphere. Research innovation is filling the gap on the use of flexible solar panels on curved and unconventional surfaces.
... elated to the system's lifetime (El Chaar, 2011). Project expectancy lifetime is assumed to be 25 years on average considering literature and typical module warranties (Fazelpour et al., May 2016;Korsavi et al., Feb. 2018;Good, Mar. 2016; "Renewable Energy and Energy Efficiency Organization." http://www.satba.gov.ir/en/home (accessed Feb. 10, 2021;Dehghan et al., Jun. 2021). Normally, a linear degradation is assumed for the mature PV technologies reaching 80 % of the initial efficiency at the lifetime endon average, 0.7 % decrease per year -(Fthenakis, 2011; Toboso-Chavero, Aug. 2019; "Enabling PV Iran," German Solar Association -BSW-Solar / Bundesverband Solarwirtschaft e.V, Berlin, Germany, (Förderkennze ...
... Table D1Indicators' quantification summary over the 25 years' service time for the studied domestic solar systems Literature review e.g.,(Korsavi et al., Feb. 2018;Dehghan et al., Jun. 2021; "Enabling PV Iran," German Solar Association -BSW-Solar / Bundesverband Solarwirtschaft e.V, Berlin, Germany, (Förderkennzeichen-FKZ): Renewable Energy and Energy Efficiency Organization." http://www.satba.gov.ir/en/home (accessed Feb. 10, 2021) I 4 . Implementation time National guideline ("Environmental, Health and Safety Guideline f ...
Article
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Renewable energy applications are lucrative alternatives to minimize urban environmental impacts. Solar energy, the most abundant, inexhaustible, and cleanest of all renewable sources, provides an opportunity to transform buildings from energy consumers into active energy producers. Nevertheless, photovoltaic (PV) and hybrid photovoltaic/thermal (PV/T) are considered the most viable alternatives for urban settlements. This study, as part of a broader research project, develops a new model to evaluate solar systems' air pollution mitigation capacity and assist decision-makers in adopting the most suitable solution. The approach is based on the integrated value model for sustainability assessment (MIVES), combined with the analytic hierarchy process (AHP) and sensitivity analysis. This multi-objective tool is applied to residential buildings in Tehran, a megacity example with unused rooftops, solar energy harvest potential, and air pollution reduction needs. Results reveal one square meter of PV and PV/T enables avoiding 211 and 488 kg CO2 emissions annually, as well as 1.2 and 1.9 g PM pollutants, respectively. Although PV achieves higher sustainability indexes as a better socio-economic alternative, PV/T can be a robust solution when stakeholders are more sensitive to environmental requirements and air pollution decrement potential. The critical obstacle to PV/T deployment is the lack of financial incentives. However, allocating 38 % of solar electricity feed-in tariffs to solar thermal energy could solve this issue. Compared to green roofs, solar systems stand out with CO2 saving and energy production potential. Researchers expect future solar collectors’ improvements, such as lower resource consumption, thus, becoming more environmentally friendly and cost-effective solutions.
... On the other hand, due to the environmental friendliness of renewable energy, it is deemed as a more appropriate alternative to fossil fuels [3,4]. Among renewable energies, solar energy has attracted a lot of attention as a source of available, clean, and cheap energy within the last years [5,6]. ...
... Specifications of fans[6]. ...
Article
An air-based photovoltaic-thermal (PV-T) system with a converging collector (i.e. a channel with a decreasing hydraulic diameter), to the best of authors’ knowledge for the first time, has been experimentally studied against a PV-T counterpart with the conventional thermal collector geometry (i.e. with fixed hydraulic diameter) as well as a PV module with no thermal management system. An iterative method for the calculation of the convective heat transfer coefficient (hd) introduced in the study revealed that hd for a conventional thermal collector can be easily increased up to 38 % using the idea of the converging collector with no need for any extra energy or cost. According to the measurements, this enhancement results in an increase in the net overall efficiency of the PV-T system by 12 % on average compared to a PV-T system with a conventional thermal collector. Meanwhile, the converging thermal collector results in an almost uniform temperature distribution for the PV, confirming the idea of the uniform cooling in air-based PV-T systems is possible, which has not been previously reported.
... The curved shape is also used to silos, biogas tanks, greenhouses and structures. The Taguchi factorial experiment and response surface methods are used to improve the precision of the test and reduce the expense of testing and speed up the experiment [27]. Conventional solar panels involve the construction of glass panels that are usually not quite consistent with cylindrical geometric shapes [28]. ...
... This price is supposed to be 20 years of the solar system's useful lifetime [42]. Dehghan et al. [27] have considered the different feed-in tariff (FiT) rate to be 0.05 $/kWh. In addition, the project's NPV is set to zero and the discount rate, which is the same as the project's IRR, is determined. ...
Article
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Photovoltaic cells are a significant renewable energy source due to their cheap cost and renewability. In both warm sunny and colder and cloudier conditions, a-Si modules outperform c-Si modules on a normalized energy basis. This study investigated 1 m 2 of amorphous photovoltaic silicon on curved surfaces. The Taguchi and response surface methods were utilized to expand the model in real terms. Results demonstrated the technology gap in the use of silicon crystal photovoltaics is eliminated. The maximum power in the Taguchi method test is 59.87 W, while the minimum power is 57.84 W when the system is deployed on a flat surface, and the maximum power in the RSM Test is 61.14 W when the system is deployed on a hemispherical surface, and the minimum power is 56.6 W when the system is deployed on a flat surface. The minimal performance was 7.1% on a level surface. The flat surface produced 810 kWh, the cylindrical surface 960 kWh, and the hemisphere 1000 kWh. The NPV at Flat surface is 697.52,witha34.81697.52, with a 34.81%, IRR and an 8.58-year capital return period. Hemisphere and cylindrical surfaces both get 955.18. The investment yield was 39.29% for cylindrical constructions and 40.47% for hemispheres. On the flat surface, doubling fixed investment improved IRR by 21.3%. The cylindrical system increased by 25.59% and the hemisphere by 24.58%. The developed simulation model is empirically evaluated using a MATLAB computer tool; the key findings from the validation procedure are reported in this study.
... Most of the studies on the cooling of photovoltaic panels are also focused on the usage of the thermal energy extracted because of this process [27,[30][31][32][33], so that the recovery time of the investment is less than of the stand-alone photovoltaic systems [34,35]. ...
... For Scenarios 1 and 2, net specific energy improvements of 4.4% and 4.1%, respectively, were reported. The techno-economic research showed that only at high feed-in tariff rates can the suggested thermal management be easily justified [72]. ...
Article
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Due to its widespread availability and inexpensive cost of energy conversion, solar power has become a popular option among renewable energy sources. Among the most complete methods of utilizing copious solar energy is the use of photovoltaic (PV) systems. However, one major obstacle to obtaining the optimal performance of PV technology is the need to maintain ideal operating temperature. Maintaining constant surface temperatures is critical to PV systems’ efficacy. This review looks at the latest developments in PV cooling technologies, including passive, active, and combined cooling methods, and methods for their assessment. As advances in research and innovation progress within this domain, it will be crucial to tackle hurdles like affordability, maintenance demands, and performance in extreme conditions, to enhance the efficiency and widespread use of PV cooling methods. In essence, PV cooling stands as a vital element in the ongoing shift towards sustainable and renewable energy sources.
... PCM was also used in PV panels [29][30][31] for better thermal management. On the other hand, in active cooling methods of PV panel, forced air flow was used in numerous studies [32][33][34][35]. Studies considering forced convection using water were also carried out for enhancing the performance of the PV panels [36][37][38][39]. ...
... According to the Iranian parliament's legislation, each kilowatt of renewable electricity is purchased from the consumer at ~0.05 $/kWh, which this price is supposed to be 20 years of the solar system's useful lifetime [38]. In [39] the different Feed-In Tariff (FiT) rate is considered to be 0.05 $/kWh. IRR is calculated by COMFAR through trial and error because you are trying to arrive at whatever rate makes the NPV equal to zero. ...
Article
Iran's energy sector, which includes power generation, transportation, industry, buildings, and homes, is a significant source of greenhouse gas emissions. Plans for efficient design and development of maximum power control systems aim to increase the share of renewable energy in electricity usage. Floating photovoltaic systems combine existing photovoltaic systems with a floating structure to generate clean energy and integrate existing dams to enhance power sources. The results indicate that installing a hybrid floating solar power plant at a level of more than 1 km2 over the dam reservoir's surface provides 194 GWh to 257 GWh of electricity per year. Installation floating photovoltaic plant would supply electricity for 2260 green cottages while also improving the environment and reducing water evaporation. Adding a floating solar power plant with 10% of the lake reservoir cover of six dams saves 70.7 million cubic meters of water per year which is enough to meet the annual needs of one million people. This study fills a research gap in the energy sector by studying the economics of hybrid renewable energy systems in Net-zero energy buildings.
... One of the main parameters is the operating temperature of PV modules [4]. Study [5] investigated through techno-economic analysis the temperature management of PV modules. The phenomenon of dirt resulting from the deposition of dust particles on solar energy equipment and systems is becoming increasingly significant; a layer of dust covering the surface of PV modules reduces PV electricity production by shielding solar radiation [6]. ...
Article
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This work aims to assess the impacts of climate change on photovoltaic (PV) electricity in two Italian cities, with different latitudes and Köppen–Geiger climate classifications. This was undertaken using the recent EURO-CORDEX set of high-resolution climate projections and PV power generation models, implemented on TRNSYS software. Data for two variables (surface air temperature and solar radiation) were analysed over a long period from 1971 to 2100. For future periods, two of the Representative Concentration Pathway scenarios (RCP4.5 and RCP8.5) used in the Intergovernmental Panel on Climate Change Fifth Assessment Report were considered. In both RCP scenarios and both locations, it is estimated that the yearly PV energy produced in the future period will not undergo significant variations on average given that the rate of decrease is foreseen almost constant; instead, a slight reduction in the PV energy was detected in the past period. It can be concluded that the PV market in Italy will grow in the next years considering that the reduction in the foreseen PV purchase costs will be also supported by the slight positive effect of climate change on PV manufacturability.
... Therefore, to enhance the performance of these systems, either or both parts can be suitably modified. One of the most impactful ways to improve the VCRC system performance is by subcooling the outlet refrigerant from the condenser, which increases the evaporator capacity [15,16], while one of the challenges in using PV modules in such systems is associated with alleviating the increase in the temperature of these modules, especially in sunny and hot conditions and, as a result, in mitigating the corresponding decrease in their electrical efficiency in such conditions [17][18][19]. Furthermore, up to 80% of the total received solar energy is typically lost to the ambient by PV modules [20,21]. To solve these problems, photovoltaic-thermal (PVT) collectors can be used [22][23][24][25][26], which have considerably higher total (electrical plus thermal) efficiencies than PV modules, and in which a cooling fluid removes thermal energy from the PV cells in order to reduce the module's temperature, thereby enhancing the electrical efficiency [27]. ...
Article
Electricity generated by photovoltaic (PV) modules can be converted into cooling using well-known refrigeration technologies based on vapor compression refrigeration cycles. One of the most critical issues arising when using PV modules is elevated temperatures in sunny and hot conditions, resulting in a corresponding decrease in electrical efficiency. Therefore, this work aims to enhance the performance of a solar compression refrigeration system using a single PV-thermal (PVT) collector fully integrated with a refrigeration system employing a low GWP refrigerant (R290) instead of the R134a. Furthermore, zinc oxide (ZnO) nanofluid is used to absorb thermal energy from the PVT collector and to improve its electrical efficiency. The outlet fluid from the PVT collector is used to subcool the refrigerant at the outlet from the condenser of the cycle. The impacts of varying the nanofluid flow rate, nanoparticle concentration, evaporator, and condenser temperatures on the performance of the system are thermodynamically evaluated. The theoretical analysis based on the first and second laws of thermodynamics indicates that using ZnO nanoparticles enables an enhanced Solar Cooling Efficiency (SCE) and Coefficient of Performance of the system by more than 30%, from 21 to 28% and from 9 to 12%, respectively, for various nanoparticle concentrations ranging from 0 to 6%. The use of the nanofluid results in a 1–6% decrease in the total heat exchanger area compared to pure water in the solar-collector circuit. Finally, it is reported that using R290 enhances the SCE by 3%, compared to a system employing R134a as the refrigerant.Graphical abstract
... In recent years, solar energy is widely employed for heating [1,2], desalination [3], cooling and refrigeration [4], air-conditioning [5], and electricity generation [6,7] for a wide range of applications from domestic to industrial and agricultural applications [8,9]. In most solar facilities, the common systems used to convert solar energy into an applicable form of energy are photovoltaic (PV) modules [10] and thermal collectors [11], or hybrid systems generating both solar heat and electricity [12]. ...
Article
The soiling phenomenon originating from dust particle deposition on solar energy facilities and systems is getting more and more significant. Some studies have attempted to provide mathematical relationships or correlations to predict the performance of soiled solar systems. These correlations are based on dust characteristics or environmental factors which are presented in the present study. In addition, among these studies, there are many questions and ambiguities, especially in time-dependent models for predicting the performance of solar systems considering the soiling phenomenon. The above-mentioned topics have been rarely subjected to a critical review in terms of the modeling, and hence the present study aims at systematically reviewing, classifying, and presenting the mathematical relationships and correlations proposed for soling effects (on the transmittance of glass covers, the reflectance of solar reflectors, electrical efficiency, and thermal efficiency) to predict the performance of soiled solar systems. Major topics and subjects for further studies are introduced to fill the existing gaps and to find unknown relationships between the governing factors.
... The curved shape is also used on silos, biogas tanks, greenhouses and structures. The Taguchi factorial experiment and response surface methods are used to improve the precision of the test and reduce the expense of testing and speed up the experiment (Dehghan et al., 2021). Conventional solar panels involve the construction of glass panels that are usually not quite consistent with cylindrical geometric shapes (Keshtegar et al., 2018). ...
Article
Full-text available
Renewable energy regulations place a premium on both the use of renewable energy sources and energy efficiency improvements. One of the growing milestones in building construction is the invention of green cottages. Building Integrated Photovoltaic (BIPV) technologies have been proved to aid buildings that partially meet their energy demand as sustainable solar energy generating technologies throughout the previous decade. Curved facades provide a challenge for typical photovoltaics. This study designed, produced, and assessed elastic solar panels supported by flexible photovoltaic systems (FPVS) on a 1 m2 layer. The LabVIEW program recognizes and transmits online data on warm and dry climates. The fill factor was 88% and 84%, respectively, when installed on the silo and biogas surfaces. The annual energy output was 810 kWh on a flat surface, 960 kWh on a cylindrical surface, and 1000 kWh on a hemisphere surface. Economic analysis indicates that the NPV at Flat surface is 697.52,withanIRRof34.81 697.52, with an IRR of 34.81% and an 8.5-year capital return period. Cylindrical surfaces and hemispheres both get a 955.18 increase. For cylindrical and hemispheric buildings, the investment yield was 39.29% and 40.47%, respectively. A 20% increase in fixed investment boosted the IRR by 21.3% in the flat system. While the cylindrical system had a 25.59% raise, the hemisphere saw a 24.58% gain
... The curved shape is also used on silos, biogas tanks, greenhouses and structures. The Taguchi factorial experiment and response surface methods are used to improve the precision of the test and reduce the expense of testing and speed up the experiment (Dehghan et al., 2021). Conventional solar panels involve the construction of glass panels that are usually not quite consistent with cylindrical geometric shapes (Keshtegar et al., 2018). ...
... According to the Iranian parliament's legislation, each kilowatt of renewable electricity is purchased from the consumer at ~0.05 $/kWh, which this price is supposed to be 20 years of the solar system's useful lifetime [46]. Dehghan et al [47] have considered the different Feed-In Tariff (FiT) rate to be 0.05 $/kWh. The project's NPV is set to zero and the discount rate, which is the same as the project's IRR, is determined. ...
... It is well proved that the fossil fuels can be replaced by solar energy as it is safe, inexhaustible, and clean [1]. The solar energy can be harvested by the photothermal and photoelectric systems [2]. However, the photothermal systems are surely more mature [3]. ...
Article
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Background Many techniques are used to improve the thermal efficiency of flat plate solar collectors. The previous studies showed the high potentials of nanofluids for thermal efficiency improvement of flat plate solar collectors. Methods In this study, a numerical simulation is carried out to investigate the thermal efficiency of the flat plate thermosyphon solar water heater with different nanofluids. The water-aluminum oxide, water-copper oxide, water-copper, and water-titanium oxide nanofluids are used. The effects of different parameters, such as the volume fraction of nanoparticles, volumetric flow rate, solar radiation intensity, ambient temperature, and inlet temperature of water on the efficiency, useful energy, and mean temperature of absorber of the solar collector are investigated. Findings The results indicated that among the various nanoparticles, the addition of copper nanoparticles, followed by copper oxide, results in the greatest improvement in the efficiency and useful energy. The efficiency and useful energy increase with increasing the volumetric flow rate and volume fraction of nanoparticles. As the volume fraction of nanoparticles increases, the mean temperature of absorber decreases. As the ambient temperature increases from 20 °C to 40 °C, the efficiency increases by 5.5%. As the inlet temperature of water increases from 30 °C to 55 °C, the efficiency decreases by 15%. The efficiency decreases with increasing the solar radiation intensity.
Article
The current study investigates the effect of water spray cooling on the performance of a photovoltaic panel (PV). The advantage of this method compared to other methods is it provides surface cleaning besides the cooling effects which affects the long-term performance of the panel. The performance of a PV panel is correlated to the temperature of the panel and increases by 0.35–0.7% for each degree drop in surface temperature depending on the solar radiation. The goal of this study is to examine the influence of various factors, including the formation and thickness of a water film on the surface of PV cells, the rate of water consumption, and the spray distance on the performance of the PV panel. The evaluation of the PV output power and electrical efficiency indicates that using an arrangement of nozzles with maximum film coverage and minimum overlap between nozzle streams delivers the best cooling performance. Specifically, it is observed that spraying by 5 nozzles with droplet diameters of 113, 49, and 32 μm, causes a mean enhancement in solar panel efficiency by 19.9%, 17.2%, and 15.7%, with a maximum of 22.72%, 18.62%, 16.87%, respectively. These findings underscore substantial opportunities for enhancing the electrical performance of PVs through using spray cooling.
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The energy conversion performance of commercial photovoltaic (PV) systems is only 15–20 percent; moreover, a rise in working temperature mitigates this low efficiency. To enhance their performance and prevent damage, researchers test new technologies and integrate heat recovery devices with PV systems. Concentrated photovoltaic systems (CPVs) are especially vulnerable to high radiation levels. This paper explores novel cooling techniques for PV systems, an area that has not been extensively investigated before. The cooling methods are categorized into front-surface and back-surface cooling methods, offering a unique perspective on how to keep PV systems cool. Moreover, the paper delves into the advancements made in PV cooling systems and CPVs, shedding light on the cutting-edge developments in this field. The results demonstrate the profound impact of various operational factors, such as radiation and wind speed, on the selection of suitable cooling systems or heat recovery methods. These findings unveil the crucial importance of considering these factors when choosing cooling techniques, adding a compelling dimension to the research. For example, it was depicted that optical cooling techniques can enhance the performance of PV systems by up to 4.2% and the solar-to-heat conversion efficiency by up to 47%. Furthermore, this research ventures into uncharted territory by subjecting both the front and back sides of the PV module to active and passive cooling techniques under differing work conditions. The comprehensive list provided here exhaustively describes the advantages, disadvantages, and developments of each technique, revealing the novelty of the approaches explored in this paper. It was reported that back cooling techniques can decline the cell temperature of PV systems by up to 57.8% and grow the electrical and thermal efficiencies by up to 82.6% and 97.75%, respectively. The groundbreaking nature of this research lies in its ability to empower decision-makers to select the optimal cooling system based on specific requirements and environmental factors, thereby bridging the gap between theory and practical application. The paper also introduces a new concept of cooling using hydrogel, a 3D porous network structure that can enhance photovoltaic energy conversion and storage, and reviews two recent studies that demonstrated the effectiveness of hydrogel cooling methods for PV panels. Moreover, the paper discusses the issue of dust deposition and mitigation, which affects the performance and lifetime of PV modules, and evaluates various methods for cleaning or reducing dust on PV panels, such as manual, passive, self-cleaning, and mechanical.
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In this review article, the potential of solar chimney technologies for building ventilation, power generation and potable water generation in sole, hybrid and poly-generation modes has been reviewed extensively by highlighting their optimal configuration, pros, cons and economics. Solar chimney ventilation system in combination with evaporative cooler and earth-air heat exchanger can save at least 20 to 75% of the energy consumed for space conditioning activity. Sole solar chimney power plant occupies huge land area and has efficiency of only 1.0%. However, under hybrid and poly-generation operation modes its efficiency has improved to 55%. Solar PV modules seem to be a suitable partner for solar chimney technologies and it enhances utilization factor by providing extra electric power output. Solar PV modules have been suggested as absorber for ventilation system and canopy for solar chimney power plants. However, proper thermal management of PV modules is essential for proper functioning under the conditions inside the former system. Geo-thermal energy, waste heat energy from thermal power plants and flared gas from oil extraction sites can be utilized in solar chimney power plants to increase its operation time even after sun-set hours without any major modifications. Solar chimney based atmospheric water extraction systems enhances the micro-climate of sites and is highly suitable for applications in arid regions. Solar chimney ventilation systems are commercial and form an integral part of green buildings and net-zero buildings. On contrary, most of the literatures on power generation and water production with solar chimney technology are theoretical hence more practical studies are needed to justify their reliability.
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PV modules are characterized by high reliability and long life. Accurately assessing the field reliability of PV modules is extremely important for manufacturers and users. However, how to further determine the applicable geographical regions of reliability assessment results obtained at certain installation locations, which is of great significance in maximizing investment benefits and guiding site selection of new PV plants, is hardly studied yet. To solve this problem, a method by identifying the geographical regions where PV modules are most consistent in the field reliability based on the regional clustering of environmental factors and their weights is presented. The novelty of this method is that not only the relevant environmental factors are selected more reasonably from two different dimensions, but the weights of every factor are calculated separately using more proper ways. Compared to the existing method, the mean coefficient of variance (CV) and Dunn index of the clustering result is reduced by 13.70% and increased by 11.89% respectively. Moreover, the actual performance degradation data of PV modules in different regions also directly demonstrate the superiority of the proposed approach. This methodology can be very efficient in rationally broadening the application values of the PV modules field reliability assessment results.
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Photovoltaic (PV) panels convert a portion of the incident solar radiation into electrical energy and the remaining energy (>70 %) is mostly converted into thermal energy. This thermal energy is trapped within the panel which, in turn, increases the panel temperature and deteriorates the power output as well as electrical efficiency. To obtain high-efficiency solar photovoltaics, effective thermal management systems is of utmost. This article presents a comprehensive review that explores recent research related to thermal management solutions as applied to photovoltaic technology. The study aims at presenting a wide range of proposed solutions and alternatives in terms of design approaches and concepts, operational methods and other techniques for performance enhancement, with commentary on their associated challenges and 2 opportunities. Both active and passive thermal management solutions are presented, which are classified and discussed in detail, along with results from a breadth of experimental efforts into photovoltaic panel performance improvements. Approaches relying on radiative, as well as convective heat transfer principles using air, water, heat pipes, phase change materials and/or nanoparticle suspensions (nanofluids) as heat-exchange media, are discussed while including summaries of their unique features, advantages, disadvantages and possible applications. In particular, hybrid photovoltaic-thermal (PV-T) collectors that use a coolant to capture waste heat from the photovoltaic panels in order to deliver an additional useful thermal output are also reviewed, and it is noted that this technology has a promising potential in terms of delivering high-efficiency solar energy conversion. The article can act as a guide to the research community, developers, manufacturers, industrialists and policymakers in the design, manufacture, application and possible promotion of high-performance photovoltaic-based technologies and systems.
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This numerical study on the effect of microchannels with porous medium and nanofluid on the solar concentrator photovoltaic (CPV) system with a solar concentration ratio of 10 is presented. Numerical simulation is two-dimensional and different layers of CPV are modeled. The effect of the position of the porous layer in the microchannel on the cooling of the PV system is investigated. The thermal behavior of the microchannel with the porous layer varies with the change of Darcy number, and the porosity coefficient according to the position of the porous layer in the microchannel is studied. The consequences demonstrate that the solar cell temperature is reduced by about 17% using the microchannel. The development of the microchannel cooling capacity is related to the rise in thermal conductivity in the porous layer. Also, in the porous layer cases, located in a block width across the microchannel, the maximum electrical efficiency rate and the minimum of the solar cell temperature occurred. The raising of the nanofluid volume fraction has improved the CPV system's electrical efficiency. Consequently, the solar cell temperature can be reduced from 1 to 52% with the increment of radiation intensity from 100 to 1000 Wm−2. The proposed cooling method is about 30% more effective than the conventional fin cooling method.
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This article presents the analysis of degradation rate over 10 years (2008 to 2017) for six different photovoltaic (PV) sites located in the United Kingdom (mainly affected by cold weather conditions) and Australia (PV affected by hot weather conditions). The analysis of the degradation rate was carried out using the year-on-year (YOY) degradation technique. It was found that the degradation rate in the UK systems varies from −1.05% and −1.16%/year. Whereas a higher degradation ranging from −1.35% to −1.46%/year is observed for the PV systems installed in Australia. Additionally, it was found that in the Australian PV systems multiple faulty PV bypass diodes are present due to the rapid change in the ambient temperature and uneven solar irradiance levels influencing the PV modules. However, in cold weather conditions (such as in the Northern UK) none of the bypass diodes were damaged over the considered PV exposure period. Furthermore, the number of PV hot spots have also been observed, where it was found that in the UK-based PV systems the number of hot spotted PV modules are less than those found in the Australian systems. Finally, the analysis of the monthly performance ratio (PR) was calculated. It was found that the mean monthly PR is equal to 88.81% and 86.35% for PV systems installed in the UK and Australia, respectively.
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The effects of micro-pin characteristics on flow and heat transfer of a circular impinging jet are studied both experimentally and numerically. The studies are carried out for a single jet impinging (D = 24 mm) on a target plate that roughened by 48 micro-pins. The target surface is heated by a silicon rubber heater under a uniform heat flux of 2000 W m⁻². Two Re numbers (20,000 and 40,000), three distances between the pins and the jet (S/D = 1, S/D = 2, S/D = 3) and three nozzle-to-surface distance ratios (0.5, 1 and 2) are considered. Experimental and numerical results confirm that using micro-pin on the target surface has a significant effect on the distributions of Nusselt number. In addition, the results show that using the micro-pin on the target plate may result in both decrease and increase in the averaged Nusselt number depending on the arrangement of the micro-pins. For the Reynolds number of 40,000, the presence of the micro-pins at S/D = 2.0 can increase the average Nusselt number by 10.8%, 10.1% and 11% at H/D = 0.5, 1.0 and 2.0, respectively.
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span>Photovoltaic (PV) panel is the heart of solar system generally has a low energy conversion efficiency available in the market. PV panel temperature control is the main key to keeping the PV panel operate efficiently. This paper presented the great influenced of the cooling system in reduced PV panel temperature. A cooling system has been developed based on forced convection induced by DC fan as cooling mechanism. DC fan was attached at the back side of PV panel will extract the heat energy distributed and cool down the PV panel. The working operation of DC fan controlled by PIC18F4550 microcontroller which depending on the average value of PV panel temperature. Experiments were performed with and without cooling mechanism attached at the backside PV panel. The whole PV system was subsequently evaluated in outdoor weather conditions. As a result, it is concluded that there is an optimum number of DC fans required as cooling mechanism in producing efficient electrical output from a PV panel. The study clearly shows how cooling mechanism improves the performance of PV panel at the hot climatic weather. In short, the reduction of PV panel temperature is very important to keep its performance operated efficiently.</span
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This paper deals with the analysis of passive based cooling techniques for photovoltaic panels (PVs). A comprehensive review and evaluation of the research activities and in general studies related to the development of passive cooling techniques for PVs was obtained. A major contribution to the herein reported research study is the provision of a general economic analysis for the passive cooling options as there is a gap in present research studies related to the economic aspect of the proposed cooling techniques (the same issue was also noticed for environmental aspects). Based on the comprehensive literature review, it was found that most of the examined passive cooling options are ones with an assumed application of PCM, then air based, liquid based (water, nanofluids, etc.) and finally radiative based. A 30 kW PV plant case study was considered in order to estimate the LCOE for each considered passive cooling technique, i.e. to examine the economic aspect (where general performance data were used with respect to the obtained analysis of the passive cooling techniques). Furthermore, LCA was also carried out in order to check the environmental aspects of the considered passive cooling techniques for PVs. Finally, according to the gained results and existing technical solutions, the currently most viable passive cooling option, both from a technical and economic point of view, is the air based cooling option with Al-fins mounted on the backside surface of the PV panel. The PCM based passive cooling technique for PVs could only be an option in future terms if a significant PCM material price drop were to occur. Therefore, the future development of passive cooling techniques could be focused on the research of hybrid cooling options. The hybrid passive cooling option assumes a mix of passive cooling techniques. Finally, the advantage of each cooling technique could be efficiently utilized in that manner.
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This paper introduces a new photovoltaic module passive cooling system that works with natural cooling water circulation. The heat was removed from cooling water by a PCM-based cooling system. A special zig zag geometry of PCM container was considered to increase the heat transfer surface. At the first stage of experiments, a composed oil consisting of 82 wt% coconut oil and 18 wt% sunflower oil was used as PCM. Then, in order to increase the performance of heat transfer between PCM and cooling water, the composed oil was mixed with Boehmite nanopowder (0.009 (w/w)). The cooling performance of the composed oil and nano - composed oil was assessed by monitoring the temperature and the generated electrical power of the panel at various radiation intensities. The results reveal the reliability of the proposed system for cooling of the PV module without need to any pumping system. Moreover, the results show that using nano - composed PCM is more efficient than the plain one. The highest increase in the maximum produced power relative to the reference case were obtained in the presence of nano - composed oil, which were 44.74, 46.63, 48.23% at the radiation intensities of 410,530,690 W/m², respectively.
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The paper deals with a passive air‐based cooling technique of photovoltaic (PV) panels in operating conditions. Cooling technique is done by specific type of using aluminium fins, and its main purpose is to increase the electrical efficiency of the PV panel. An increase in electrical efficiency can be achieved because of temperature degradation effect, where the PV panel yields less power at higher operating temperatures (the PV panel's efficiency can drop by up to 0.5%/°C). To confirm a cooling technique, a medium‐sized PV system was used in a 2‐month experiment. The experiment was done in realistic operating conditions, and all working parameters were thoroughly measured. After the analysis of the data, no significant raise in electrical efficiency was recorded throughout the experiment. A numerical approach was conducted, based on gained experimental data. Developed numerical model gave explanations of experimental results and provided an insight in heat flow through the PV cell. Later on, developed numerical model was used to propose new cooling variations of the fin‐based technique and to further examine the overall potential of air based passive cooling techniques. It was shown that cooling effect by up to 5°C is a realistic expectation for this technique in described operating conditions. Specific passive fin‐based PV passive cooling technique was examined. Experimental investigation in period of several months was conducted. Several set‐up and technique drawbacks were noticed. Simplified numerical model was made, which corresponds well with experimental data. Model examination gives a cooling potential of up to 5°C for PV temperature.
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As ZnO nanoparticles had the advantages of high thermal conductivity and low cost, the possibility of using ZnO nanoparticles in spectral splitting photovoltaic/thermal (PV/T) systems was initially studied from the perspective of optical properties. Water-ZnO and glycol-ZnO nanofluids were prepared via a two-step method and used for model validation and stability testing. The scheme employed to investigate the optical properties and radiative transfer of the nanofluids was developed using Mie scattering theory combined with the Monte Carlo ray tracing (MCRT) method. The overall effective spectral trans-mittance coefficients of PV cells were utilized for comprehensive evaluation of the spectral transmit-tances of the nanofluids in spectral splitting PV/T systems. The overall effective spectral transmittance of a PV cell water-ZnO nanofluids was 21.54% higher than that those of cells containing water-polypyr-role and water-Cu 9 S 5 nanofluids, respectively. The effects of the nanoparticle diameter, mass concentration and the optical length of the nanofluid on the spectral transmittance of glycol-ZnO nanofluid were also investigated.
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Simultaneous effects of using nanoparticle (Al 2 O 3) in water along with the converging flow passages on the forced convection heat transfer coefficient in a microchannel heat sink (MCHS) are investigated using a finite volume numerical simulation. The accurate KKL (Koo-Kleinstreuer-Li) model, considering particles' material density, volume fraction, diameter and Brownian motion, is implemented to model the thermophysical properties of Al 2 O 3-water nanofluid. The numerical simulation is performed based on a non-uniform structured grid. Results have shown that nanoparticles can enhance the convection heat transfer coefficient of the base fluid and the enhancement obtained by the nanoparticles are 33% higher for the case of the converging flow passages than that of straight passages. Simulation results have proved that implementation of an enhanced working fluid (i.e. Al 2 O 3-water nanofluid) and using geometrical enhancement (i.e. converging flow passages) reveal synergetic thermal response and shows an effective enhancement on the convection heat transfer coefficient as high as 2.35 times greater than the heat transfer coefficient of a pure water flows through a straight channel with no convergence. The present results suggest implementing nanofluids along with converging flow passages to achieve the effective enhancement in the convection heat transfer coefficient and to boost the improvement obtained by each individual enhancement technique, especially in the thermally developed regions wherein the convection heat transfer coefficient cannot be increased by increasing the inlet velocity/pressure in the laminar flow regime.
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Simultaneous effects of using nanoparticle (Al2O3) in water along with the converging flow passages on the forced convection heat transfer coefficient in a microchannel heat sink (MCHS) are investigated using a finite volume numerical simulation. The accurate KKL (Koo-Kleinstreuer-Li) model, considering particles' material density, volume fraction, diameter and Brownian motion, is implemented to model the thermophysical properties of Al2O3-water nanofluid. The numerical simulation is performed based on a non-uniform structured grid. Results have shown that nanoparticles can enhance the convection heat transfer coefficient of the base fluid and the enhancement obtained by the nanoparticles are 33% higher for the case of the converging flow passages than that of straight passages. Simulation results have proved that implementation of an enhanced working fluid (i.e. Al2O3-water nanofluid) and using geometrical enhancement (i.e. converging flow passages) reveal synergetic thermal response and shows an effective enhancement on the convection heat transfer coefficient as high as 2.35 times greater than the heat transfer coefficient of a pure water flows through a straight channel with no convergence. The present results suggest implementing nanofluids along with converging flow passages to achieve the effective enhancement in the convection heat transfer coefficient and to boost the improvement obtained by each individual enhancement technique, especially in the thermally developed regions wherein the convection heat transfer coefficient cannot be increased by increasing the inlet velocity/pressure in the laminar flow regime.
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The effects of simultaneous implementation of corrugated walls and nanoparticles upon the performance of solar heaters are investigated. Triangular and sinusoidal wall profiles along with varying concentration of nanoparticles are analyzed. The multi-phase mixture and the SST κ-ω models are used to simulate turbulent nanofluid flows inside the corrugated channels. The staggered computational grid is employed for storing the velocity and pressure terms at cell faces and cell center, respectively. The governing equations are first discretized by employing a second-order upwind differencing technique and are then solved by means of pressure-based finite volume approach. The convergence criterion is also presented for the validation of obtained results. The effects of wall profiles and nanoparticle concentration on the pertinent parameters including Nusselt number, pressure drop, performance evaluation criterion (PEC), and thermal and frictional irreversibilities are studied. This reveals that, in general, the triangular duct features superior heat transfer and inferior hydraulic characteristics in comparison with the sinusoidal duct. It is demonstrated that as long as the base fluid (water) is used the highest value of PEC corresponds to the straight duct. Yet, by introducing nanofluids the PEC values of the corrugated ducts exceed those of the straight duct. The analysis further shows that on the basis of the performance evaluation criterion, the sinusoidal duct appears to be a better choice in comparison with the triangular duct. However, the situation is reversed when thermodynamic irreversibilities are considered. It is argued that vortex formation in the two investigated wavy walls and shear layer developed in the triangular case are the essential physical reasons for the observed thermal, hydraulic and entropic behaviors.
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This paper presents a three-dimensional, numerical thermo-hydrodynamic and second low analysis of nanofluid flow inside a square duct equipped with transverse twisted-baffles. A finite volume method is employed to simulate forced convection of heat in the system with the inclusion of Brownian motion of the nanoparticles. The ultimate aim is to gain further understanding of the underlying physical processes and also to determine the optimal design and working conditions of the system. The effects of variations in the pitch intensity (γ) from 180° to 540° and volume fraction of nanoparticles (φ) from 0 to 0.05 on the nanofluid flow, heat convection and thermodynamic irreversibilities are investigated. The numerical results show that the baffle with γ = 360° features the maximum value of heat transfer coefficient among all values of γ. Additionally, the baffle with γ = 540° shows the minimum pressure drop for the entire range of γ. Finally, it is shown that the thermal entropy generation decreases by increasing the volume fraction of nanoparticles or inserting baffles inside the duct.
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During its operation, a photovoltaic (PV) panel is exposed to various and in general, stochastic thermal and wind conditions, which have a significant influence on the PV panel operating temperature. The increased PV panel operating temperatures normally have an unfavorable effect on the PV panel performance and lifetime, thus various cooling methods were proposed in order to increase the photovoltaic energy conversion efficiency. A reasonable step before the consideration of a specific cooling strategy is to obtain a PV panel performance analysis with respect to its surroundings (specific geographical micro location) for various operating conditions. This paper presents such a study, which was conducted through an experimentally validated numerical model. Numerous CFD simulations regarding heat and fluid flow around a monocrystalline PV panel coupled with a heat flow simulation inside the PV panel elements were conducted. The aim of the paper was to investigate an effective heat transfer field and the variations in the PV panel temperatures with respect to various wind velocities and heat source conditions. A detailed study regarding pressure, viscous and body (buoyancy) forces as well as their effects on flow separation was also conducted. The study also investigated the changes in the effective heat transfer near the PV panel. The gained results in this study turned out to be useful for the consideration of a specific cooling strategy for PV panels, which can ultimately lead to an increase in PV panel efficiency and lifetime. Additionally, the conducted study could be used to improve the delivered electricity prediction from the PV system at a selected location defined by specific wind velocities and solar insolation distributions.
Article
This paper deals with active cooling techniques for photovoltaic panels (PVs) where a detailed review was obtained as well as analysis by examining the findings of existing literature. Based on the obtained review, an elaboration of the main performance parameters was obtained for each specific considered coolant (air, water or nanofluids). It was found that the less investigated cooling techniques are the ones related to CPV (Concentrated Photovoltaic) systems and only a few studies exist with nanofluids as the considered coolant. The majority of tested active cooling options are based on water as the coolant and for PV/T (Photovoltaic/Thermal) configurations. The economic and environmental aspects of the active cooling techniques were not analyzed in the majority of research studies thus there is an obvious gap in the existing literature. Therefore, the main outcomes of the herein obtained research are reflected through summarized analysis of all important aspects related to active cooling options for PV applications (performance, economic and environmental). According to the obtained results, the highest increase in PV panel performance is achieved by water base cooling techniques and they range from about 10% to 20% on average. To analyze economic and environmental aspects, a 30 kW PV system was studied as a case study. Regarding the economic aspect, the LCOE (Levelized Cost of Electricity) for the considered case study of a 30 kW PV system ranged from 0.096 €/kWh to 0.159 €/kWh. For the given circumstances, it was found that the considered active based cooling options were not economically viable (it is crucial to ensure optimization for the specific liquid (water) based active cooling technique followed by ‘’smart regulation’’ in order to provide a more reasonable LCOE). However, with the proper optimization of active cooling techniques, it is more than reasonable to expect an additional LCOE reduction as it could significantly reduce the operating cost. The environmental analysis (LCA) showed that out of all the herein evaluated cooling techniques, the air based cooling techniques are the most harmful to the environment which is primarily due to more intense global warming and environmental acidification effect. Other environmental impacts are approximately of the same magnitude for the specific analysed active cooling options.
Article
Cooling of PV panels is a critical issue in the design and operation of concentrated photovoltaic (CPV) technology. Due to high cell temperature and non-uniform temperature distribution, current mismatching problem and hot spot occurs on the cell resulting in either reduction of efficiency or permanent structural damage due to thermal stresses. Temperature non-uniformity on the surface of PV panel has a major impact on the performance of CPV systems and directly increases cell temperature and series resistance. This review paper highlights the importance of uniform PV cooling by exploring the possible causes and effects of non-uniformity. Cooling techniques with low average cell temperature and uniform temperature distribution are analyzed. Economic and environmental impact on the importance of cooling of PV systems are discussed and an experimental case study is presented for comparison between uniform and non-uniform cooling methods. Immersion cooling is a promising solution for uniform cooling and has been reported to reduce the cell temperature to 20–45 °C for CPV systems. Heat pipes reduced the temperature down to 32 °C with the best case temperature non-uniformity of 3 °C. Passive cooling by heat sinks was found to reduce the cell temperature as low as 37 °C for high concentrations but with an expense of large heat sink area. Active cooling by microchannels, impingement cooling and hybrid microchannel-impingement cooling were found to be most effective in dissipating high heat flux from PV surface. Cell temperature was reported to decrease to 30 °C for 200× CPV using impingement cooling. For hybrid cooling, deviation of 0.46 °C surface temperature was obtained. Using PCM materials temperature of panel was controlled within 28–65 °C whereas optimization of heat exchanger designs also showed low and uniform temperature across surface. The impact of non-uniformity was found to be significant for all PV systems however the effect is more pronounced in CPV systems.
Conference Paper
To sustain the commercial success of photovoltaic (PV) technology it is vital to know how power output decreases with time. Unfortunately, it can take years to accurately measure the long-term degradation of new products, but past experience on older products can provide a basis for prediction of degradation rates of new products. An extensive search resulted in more than 2000 reported degradation rates with more than 1100 reported rates that include some or all IV parameters. In this paper we discuss how the details of the degradation data give clues about the degradation mechanisms and how they depend on technology and climate zones as well as how they affect current and voltage differently. The largest contributor to maximum power decline for crystalline Si technologies is short circuit current (or maximum current) degradation and to a lesser degree loss in fill factor. Thinfilm technologies are characterized by a much higher contribution from fill factor particularly for humid climates. Crystalline Si technologies in hot & humid climates also display a higher probability to show a mixture of losses (not just short circuit current losses) compared to other climates. The distribution for the module I-V parameters (electrical mismatch) was found to change with field exposure. The distributions not only widened but also developed a tail at the lower end, skewing the distribution.
Article
Electrical and thermal simulations of a building integrated photovoltaic system were undertaken with a transient system simulation program using real field input weather data. Predicted results were compared with actual measured data. A site dependent global-diffuse correlation is proposed. The best-tilted surface radiation model for estimating insolation on the inclined surface was selected by statistical tests. To predict the module temperature, a linear correlation equation is developed which relates the temperature difference between module and ambient to insolation. Different combinations of tilted surface radiation model, global-diffuse correlation model and predicted module temperature were used to carry out the simulation and corresponding simulated results compared with the measured data to determine the best combination which gave the least error. Results show that modification of global-diffuse correlation and module temperature prediction improved the overall accuracy of the simulation model. The monthly error between measured and predicted PV output was lied below 16%. Over the period of simulation, the monthly average error between measured and predicted PV output was estimated to be 6.79% whereas, the monthly average error between measured and predicted inverter output was 4.74%.
Article
After a gap of more than two decades, Concentrator Photovoltaics (CPV) technology is once again under spotlight for making use of the best available solar cell technologies and improving the overall performance. CPV finds its use in a number of applications ranging from building integration to huge power generation units. Although the principles of solar concentration are well understood, many practical design, operation, control issues require further understanding and research. A particular issue for CPV technology is the non-uniformity of the incident flux which tends to cause hot spots, current mismatch and reduce the overall efficiency of the system. Understanding of this effect requires further research, and shall help to employ the most successful means of using solar concentrators. This study reviews the causes and effects of the non-uniformity in the CPV systems. It highlights the importance of this issue in solar cell design and reviews the methods for the solar cell characterization under non-uniform flux conditions. Finally, it puts forward a few methods of improving the CPV performance by reducing the non-uniformity effect on the concentrator solar cells.
Article
Renewable energy (RE) resources have enormous potential and can meet the present world energy demand by using the locally available RE resources. One of the most promising RE technologies is photovoltaic (PV) technology. This paper presents a review of the available literature covering the various types of up and coming PV modules based on generation of solar cell and their applications in terms of electrical as well thermal outputs. The review covers detailed description and thermal model of PV and hybrid photovoltaic thermal (HPVT) systems, using water and air as the working fluid. Numerical model analysis and qualitative evaluation of thermal and electrical output in terms of an overall thermal energy and exergy has been carried out. Based on the thorough review, it is clear that PVT modules are very promising devices and there exists a lot of scope to further improve their performances particularly if integrated to roof top. Appropriate recommendations are made which will aid PVT systems to improve their overall thermal and electrical efficiency and reducing their cost, making them more competitive in the present market.
Temperature uniformity enhancement of densely packed high concentrator photovoltaic module using four quadrants microchannel heat sink Solar Energy
  • Ali Abdallah
  • M Essam
  • M F Abo-Zahhad
  • A H Elkady
  • Ali Shinichi Ookawara El-Shazly
  • Radwan
Abdallah YM Ali Essam M. Abo-Zahhad M.F. Elkady A.H. Shinichi Ookawara El-Shazly, and Ali Radwan. Temperature uniformity enhancement of densely packed high concentrator photovoltaic module using four quadrants microchannel heat sink Solar Energy 202 2020 446 464.
Evaluation of high-temperature exposure of rack-mounted photovoltaic modules
  • Kurtz Sarah
  • Whitfield Kent
  • Miller David
  • Joyce James
  • Wohlgemuth John
  • Kempe Michael
  • Dhere Neelkanth
Kurtz Sarah, Whitfield Kent, Miller David, Joyce James, Wohlgemuth John, Kempe Michael, Dhere Neelkanth, Bosco Nick, Zgonena Timothy, editors. Evaluation of high-temperature exposure of rack-mounted photovoltaic modules. IEEE; 2009. p. 002399-404.