A novel thermal model for PV panels with back surface spray cooling

Abstract

To improve the performances of photovoltaic panels, water-based cooling systems have been considered as an interesting solution. This study proposes a novel mono-dimensional thermal model that includes the spray cooling phenomena on the back surface. The model is based on the energy balance method with a Finite Difference approach providing the thermal field across the thickness, and was validated with data of an experimental setup with a PV panel equipped with two spray nozzles. Simulations were carried out over a large number of days in the summer period with a short time step (5 s). Results showed an average RMSE of 1.37 °C, RMSEP of 0.005% and NSE of 96.5% for the back surface temperature, and an average RMSE of 3.39 W, RMSEP of 0.36% and NSE of 99.6% for the electric power. A further assessment of the cooling phenomenon highlighted the contribution of sensible and latent energy exchanges to the panel energy balance. Finally, a comparison of the performances with a non-cooled PV panel showed an average increase of 7.8% of the electric power in solar radiation peak hours and a reduction of 28.2% of the average cell temperature.