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    Introduction to solar panels
    (Elsevier, 2023) Karaağaç, Mehmet Onur; Ergün, Alper; Arslan, Oğuzhan; Kayfeci, Muhammet
    Decarbonization has gained global importance in order to reduce climate change that is mainly caused by the usage of fossil fuels. Renewable energy sources have the potential to reduce carbon emissions. For this purpose, the energy sector has focused on cost-competitive solar panel technologies in recent years. Solar panels are systems made of semiconductor materials that convert the solar radiation coming to their surfaces into electrical energy. The fact that solar energy is an inexhaustible resource and is free in abundance is shown as the most economical system compared to traditional energy sources. Solar energy has an important share when considering the electricity obtained from renewable energy sources in the last decade. In addition, when the efficiency of PV technologies increases and their costs decrease, the use of these systems will become more widespread. Since it provides sustainable production and reduces CO2 emissions, solar panels can play an important role in meeting the national energy need. In this chapter, the history of solar panels, semiconductor materials, solar cells, PV technologies, the global energy situation, and their place in renewable energy sources are shown in the overview. © 2023 Elsevier Inc. All rights reserved.
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    Liquid-based solar panel cooling and PV/T systems
    (Elsevier, 2023) Ergün, Alper; Kayfeci, Muhammet; Karaağaç, Mehmet Onur
    Solar panels (also called PV panels) have been widely used in recent years to generate electricity from solar energy. One of the biggest disadvantages of PV panels is their low efficiency. In general, the efficiency of a PV panel varies between 15% and 20%. The temperature increase in PV panels is the most important parameter that causes their efficiency to decrease. Each 1°C increase in temperature causes approximately 0.45%–0.6% efficiency decrease. For this reason, cooling of PV panels increases their efficiency. Liquid-based cooling processes are frequently used for the water cooling process. But recent years researchers are examining air, oils, water, and water/nanofluids dispersions. In this chapter, liquid-based cooling of PV panels will be examined in detail. New studies in this field will be given with examples and developments in photovoltaic thermal (PV/T) applications will be mentioned. © 2023 Elsevier Inc. All rights reserved.
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    Öğe
    Solar panel cooling using hybrid cooling systems
    (Elsevier, 2023) Yıldız, Gökhan; Karaağaç, Mehmet Onur; Ergün, Alper; Kayfeci, Muhammet
    Photovoltaic (PV) panels are systems that convert the energy from the sun into electrical energy. A large part of the energy coming to the PV panel is converted into heat, causing the panel temperature to increase and the electrical efficiency to decrease. There are many benefits of cooling the panel to increase the performance and PV panel’s controllability. By removing the heat from the panel, the efficiency of the panel rises and the heat received is used as useful heat. In addition, the cooling of the panels also extends the panel life. The heat produced by the PV panels can cause an increase in the cell temperature above 50°C, and this situation causes a decrease in electrical efficiency (0.4% per 1°C for monocrystalline). Photovoltaic thermal (PVT) panels have been developed to cool the PV panels, and cooling process is carried out by passing water or air behind the panel. This section focuses on the different hybrid cooling techniques used in PVT panels and the effects of these techniques on performance. © 2023 Elsevier Inc. All rights reserved.
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    The Analysis of Next-Generation Refrigerants in Terms of Energy, Exergy, and LCCP Perspective
    (2023) Şimşek, Merve Özer; Karaağaç, Mehmet Onur; Ergün, Alper; Aktas, Mustafa
    In this study, commonly used hydrofluorocarbon (HFC)-based refrigerants R404A and R410A, as well as hydrofluoroolefin (HFO)-based environmentally friendly next-generation refrigerant R1234yf with a low global warming potential (GWP), were analyzed in terms of energy, exergy, and life cycle climate performance (LCCP) in refrigeration and air conditioning systems. All three refrigerants were examined at four different evaporation temperatures (-30°C, -15°C, -5°C, 0°C) with a constant condenser temperature of 50°C using a simulation program. For different evaporation temperatures, the performance of the refrigerants was evaluated using the first and second laws of thermodynamics, and performance coefficients, exergy efficiency, and exergy destruction were calculated. Additionally, the amount of kgCO₂e equivalent was calculated using the LCCP method. In the study, it was found that the compressor energy consumption of R410A and R1234yf refrigerants was similar and approximately 7% lower than that of the R404A refrigerant. The highest coefficient of performance (COP) value was determined for R1234yf. It was observed that R1234yf refrigerant had the highest exergy efficiency starting from -15°C. The kgCO₂e equivalent emission values calculated using the LCCP method revealed that R404A had the highest CO₂ emissions, while R1234yf had the lowest. Furthermore, based on the simulation study and theoretical calculations, it was determined that R410A and R1234yf refrigerants could be considered as alternative choices to R404A refrigerants in systems where two refrigerants are used.