Experimental characterization of a geothermal cooling system for enhancement of the efficiency of solar photovoltaic panels

Abstract

The efficiency of solar photovoltaic panels reduces when their temperature increases during normal operation conditions, resulting in a very significant power output reduction. This phenomenon is especially relevant in regions with high photovoltaic potential where irradiance and ambient temperature are particularly high as well. To overcome this issue, a compact cooling system for commercial photovoltaic panels based on low-enthalpy geothermal cooling is proposed. Overheating is evacuated from the solar panel by a single-phase close-loop cooling system that gets benefit of a natural underground heat sink, which is at a constant and low temperature. A prototype, integrating a single axis sun tracking mechanism, has been assembled and tested in outdoor conditions in June 2022 in Alcalá de Henares, Madrid, Spain. As it has been experimentally demonstrated, with a coolant flowrate of 1.8 l/min per square meter of panel surface, the cooling system reduces the temperature of the cooled panel up to 20 °C, which resulted in a real improvement of the panel’s efficiency up to 13.8%. Finally, a sensitivity analysis of the net power gain and the net extra energy produced by the cooled panel is presented.