Thermal analysis of radiative cooling coating on the rear surface of photovoltaic tile

Abstract

Temperature is one of the key factors to limit the conversion efficiency of photovoltaic modules. Passive radiative cooling (PRC) technology commonly used in the energy-saving applications is hopeful to improve this situation. In this paper, photovoltaic tile covered with PRC coating was studied to evaluate the feasibility of PRC technology. A thermal model was proposed to theoretically calculating the temperature distribution of PV tile module along the thickness direction. Two kinds of PRC coatings with different ideal infrared spectrums applied on the front and rear surface of PV tile was compared to assess the thermal and electrical performances. Then the optimum infrared spectrum and coating location of PRC coating for PV tile were determined, which means that the PRC coating with ideal broadband emittance applied on the rear surface of PV tile would be the best choice. A commercial radiative coating (CRC) with broadband emittance was applied on the rear surface of PV tile to ensure the cooling effect. The results indicated that the CRC on the rear surface could cool PV tile module down by 3.6 °C, and increase the efficiency by ∼ 0.33% under the average irradiance of 930 W/m2. Environmental parametric investigations demonstrated that the ground emissivity had a significant impact on the cooling effect of the optimal radiative coating (ORC) on the rear surface of PV tile. Moreover, the cooling capacity of the ORC was proved to be immune to the impact of humidity.