Thermodynamic Optimization of Electrical and Thermal Energy Production of PV Panels and Potential for Valorization of the PV Low‐Grade Thermal Energy into Cold

Abstract

In the present study, the evaluation of potential improvement of the overall efficiency of a common PV panel, valorizing the heat extracted by a heat exchanger that is integrated on its back side, either into work using an endoreversible Carnot engine or into cold by using an endoreversible tri‐thermal machine consisting of a heat‐driven refrigeration machine operating between three temperature sources and sink (such as a liquid/gas absorption machine), was carried out. A simplified thermodynamic analysis of the PV/thermal collector shows that there are two optimal operating temperatures Th and T*h of the panels, which maximize either the thermal exergy or the overall exergy of the PV panel, respectively. The cold produced by the endoreversible tri‐thermal machine during the operating conditions of the PV/thermal collector at Th is higher with a coefficient of performance (COP) of 0.24 thanks to the higher heat recovery potential. In the case of using the cold produced by a tri‐thermal machine to actively cool of an additional PV panel in order to increase its electrical performances, the operating conditions at the optimal temperature T*h provide a larger and more stable gain: the gain is about 12.2% compared with the conventional PV panel when the operating temperature of the second cooled panel varies from 15 to 35 °C.