Thermodynamic Analysis of a Hybrid Photovoltaic/thermal Solar Collector

Hybrid photovoltaic/thermal collectors (PV/T) usually consist of common photovoltaic modules cooled by a suitable fluid,and convert solar radiation simultaneously into both thermal and electric energy. The heat transfer between PV cells andcooling fluid allows lowering the temperature of the PV cells, thus improving their efficiency; it also generates low-grade heatmade available for specific applications. As a consequence, PV/T modules have a very interesting overall energy efficiency.In this paper, the Second Law analysis of a water-cooled PV/T module is discussed; the study aims to underline one maindrawback for the optimal exploitation of such a technology: the electricity production from PV cells increases at lowtemperatures, whereas the usability of the thermal energy is higher at high temperatures.The results may allow a real optimization of PV/T collectors, and lead to the definition of those operational conditions thatmaximize the total exergy harvested by the system.