Department of Mechanical, Islamic Azad University, South Tehran Branch, Tehran, Iran
solar radiation increases the surface temperature of the photovoltaic module (PV). This increase in temperature reduces the electrical efficiency and useful life of photovoltaic cells. One way to reduce the temperature of photovoltaic modules is to reduce the surface temperature of the module by circulating fluids such as water or air. Devices that operate on this basis are called combined photovoltaic - thermal collectors (PV/T). Combined photovoltaic-thermal collectors are usually made by integrating a photovoltaic module and a heat collector to prevent direct contact of the coolant fluid with the module surface. The heat absorber is very important due to the heat dissipation from the module surface to the fluid, so the thermal and electrical performance of a PV/T collector depends on the proper design of the absorber. In this research, first the classification and different structures of PV/T collectors were investigated. Then, thermal and electrical efficiency of nine practical of PV/T collector were theoretically compared with each other. Then the electrical efficiency of sheet and tube type of PV/T collector was tested by sample PV module. According to the results of this study, if the inlet fluid temperature is low, the PV/T collector will have a higher total efficiency compared to the separate heat collector or PV module.