Investigation of factors affecting photovoltaic thermal system efficiency

Abstract

This experimental study investigates the effects of ambient temperature (Tamb) and solar irradiance on the efficiency of photovoltaic panels (ηPV). Experiments have shown that increasing these parameters, which affect ηPV, also raises panel Tcell, leading to decreased electrical energy production. A photovoltaic thermal (PV/T) system was created to enhance the ηPV by reducing Tcell. The excess heat generated in the cells is stored as hot water in this system. In the experiments, water was used as the heat transfer fluid (HTF) to lower the temperature of the PV panel. A closed loop with a 25-liter tank volume circulated the water at a constant mass flow rate of 0.0161 kg/s. The heat transferred from the panel cells to the HTF was accumulated in a 50-liter water tank. The ηth of a standard PV panel and a PV/T system, with and without a fan-cooled heat exchanger, was assessed. The results showed that the ηelec of the system without a fan-cooled heat exchanger increased by 2%. However, for systems designed for maximum efficiency, the presence of the fan-cooled heat exchanger caused a 13% reduction in ηth. Additionally, the temperature of the water in the tank increased by 50%. The efficiency of the designed PV/T system was analyzed without the use of a fan-cooled heat exchanger. The 8-hour average thermal efficiency was calculated to be 66.53%, with an electrical efficiency of 3.42%. The results are presented in graphs for better data visualization.