• Energy Research

Abstract In this study, experimental analysis and performance predictions of solar photovoltaic (PV) module equipped with porous fins were performed. The experimental setup was tested in Technology Faculty of Firat University, Elazig of Turkey which is located at 36° and 42° North latitudes. The PV module was oriented facing south and tilted to an angle of 36° with respect to the horizontal in order to maximize the solar radiation incident on the glass cover. Experimental analysis was conducted for configurations where PV module is equipped with porous metal foams. A multi-input multi-output dynamic system based on artificial neural networks was obtained for the PV configuration with and without fin by using the measured data (ambient temperature, PV panels back surface temperatures, current, voltage, radiation and wind velocity) from the experimental test rig. It was observed that adding porous fins to the PV module results in performance enhancements. The developed mathematical model based on dynamic neural networks can be used for further development and performance predictions of these systems.

Abstract An experimental examination has been performed on the performance assessment of different shading shapes on photovoltaic panels by using energy-exergy analysis methods in this study. The problem is important due to decreasing of performance of PV panel with shading effect. A non-transparent material and powder were used for static shading while the time-varying shading effect of a chimney for dynamic shading was applied on to the system. Novelty of the work is to use diagonal shading on energy and exergy efficiency. Moreover, thermal camera technique was used to observe the effects of temperature distribution as a novel technique for PV panels. The photovoltaic panel was kept outside for one month in terms of dusty shading. For other static shading, artificial shadows of three different triangular shapes (40 * 40 cm for Case I, 36 * 60 cm for Case II and 60 * 36 cm for Case III) were created. The energy and exergy efficiencies of all systems under the same solar radiation were compared. The Case I-III under the same solar radiation was imaged by using a thermal camera and the effect of shading on photovoltaic panels and hot spot formation were examined. The results showed that the highest energy efficiency value was found to be 10.54% for the reference panel, 9.70% for the dusty panel, 4.16% for Case I, 4.27% for Case II and approximately zero for Case III. In the panel of dynamic shading, the lowest and the highest efficiency values were found as 0.86% and 10.27%, respectively.

Abstract This article contains the experimental investigations of different cooling methods used for photovoltaic (PV) panels. Phase change material (PCM), thermoelectric (TE) and aluminum fins were chosen as the cooling methods. The CaCl2·6H2O is chosen as one of the PCM which is widely used in the cooling of PVs and the other is the PCM with melting temperature above the surface temperature of the PV panel. By using TE material in different numbers (6, 8 and 12) and aluminum fins in different layouts, surface temperatures and output powers of PV panels were compared. It is observed that the PCM which is not chosen appropriately has insulation feature in the PV panel and enhances the temperature of the panel and decreases the output power. When the most successful cooling methods were tested under the same environmental conditions, PV with fin system produced the highest power generation of 47.88 W while PV with PCM and TEM produced the lowest power generation of 44.26 W.

Abstract Solar air heating (solar collector) is a renewable heating technology and provides heat using solar energy. With fuel costs and other factors, solar air heaters (SAHs) are getting more attention. The energetic and exergetic performance of SAHs is influenced by a number of factors. The present study reviews the previously conducted studies and applications in terms of design, performance assessment, heat transfer enhancement techniques, experimental and numerical works, thermal heat storage, effectiveness compassion and recent advances. It may be concluded that energy analysis method has been used in a number of studies while exergy analysis method has been applied to the relatively low numbers of systems. Energy efficiencies of solar air collectors reviewed varied from 47% and 89%. It is expected that this comprehensive study will be very beneficial to everyone involved or interested in the energetic and exergetic design, simulation, analysis, test and performance assessment of SAHs.

Abstract This study deals with performance assessment of porous baffles inserted solar air heaters (SAHs) using energy and exergy analysis methods. The porous baffles (PBs) with different thicknesses are used as passive element inside heaters. Closed-cell aluminum foams are chosen as porous materials with thicknesses of 6 mm and 10 mm and a total surface area of 50 cm 2 . They are placed sequentially and staggered manner onto the SAH. The measured parameters are the inlet and outlet temperatures, the absorbing plate temperatures, the ambient temperature and the solar radiation. These measurements are performed at two various air mass flow rates of 0.016 kg/s and 0.025 kg/s. Using the first and second laws of thermodynamics, energy and exergy efficiencies of the SAHs are calculated and presented for different parameters. In the experiments, five types of solar air heaters are tested and compared with each other in terms of their efficiencies. The obtained results showed that the highest collector efficiency and air temperature rise are achieved by SAHs with a thickness of 6 mm and an air mass flow rate of 0.025 kg/s whereas the lowest values are obtained for the SAH with non-baffle collectors and an air mass flow rate of 0.016 kg/s.

Abstract The increasing installed area of solar technologies around the world gives us an idea about the unlimited potential available in solar energy. Solar light and thermal energy can provide sufficient electricity needed in daily life. In additionally, photovoltaics, photovoltaic/thermal, concentration photovoltaic, concentration solar power and solar thermoelectric have been developing for energy conversion. The main aim of the present study is to make comprehensively review on exergy analysis and performance assessment of a wide range of solar electricity production. Exergy can be used to assess and improve energy systems, and can help better understand the benefits of utilizing green energy by providing more useful and meaningful information than energy provides. After that the studied systems are exergetically analyzed and evaluated solar electricity includes photovoltaics (PVs) and hybrid (PV/Twater or PV/Tair) solar collectors. The advantages and disadvantages of these systems will be presented on exergy concept. The CSP systems, the systems with nanofluid and PCM were exhibited.

Abstract The photovoltaic panels are one of the most efficient energy systems that generate electricity by absorbing the solar radiation. Nevertheless, when the sun's rays are converted to electricity, a high amount of waste heat is generated. Therefore, the efficiency of photovoltaic (PV) panels needs to be studied to minimize the amount of waste heat. There is a non-linear relationship between the temperature, the current and the voltage values produced by the PV panels. In the present study, the performance of 75 W PV panels with polycrystalline cell structure under Elazig, Turkey climatic conditions were experimentally investigated. The system performances such as temperature, power and efficiencies were analyzed by applying different fin parameters (length, sequences) to PV panels. The aluminum fins were applied with 10 different configurations as given by A1-A10. The cell temperatures, output powers, power loss ratios and energy-exergy efficiencies were calculated based on measurements of the experimental study. It was observed that the temperature did not distributed homogeneously on the PV panel. In terms of the efficiency, the fins are designed as staggered array and the 7 cm × 20 cm dimensions showed the best results. The highest energy and exergy efficiencies values of the finned panels (A5) were calculated as 11.55%, and 10.91%, respectively.