Performance improvement of photovoltaic cells using night radiative cooling technology in a PV/T collector

The solar radiation absorbed by the photovoltaic thermal systems and not transformed into electricity creates a thermal problem that significantly influences the reliability and efficiency of the photovoltaic cells. In order to passively solve this problem in the hot arid climate, the night radiative cooling technology was proposed in this work, where the water of the system was cooled by circulating in the collector exploiting the proposed technique, and it was used the next day for cooling the photovoltaic cells. For this aim, a mathematical model was developed to present the dynamic thermal behaviour of the PV/T water-based collector, based on the energy balance of its components. Then, the proposed model was validated using the experimental data available in the literature and it was used to study the effect of the glazing and the masse flow rate of water on the cooling performance. The main result indicates that the proposed method reduces the daily temperature of the photovoltaic cells by 3-5 degrees C which improves their monthly gain of electrical energy by 5.5%-6.15% compared with a conventional photovoltaic thermal collector. Consequently, the proposed method allows profiting of the annual potential of the night radiative phenomenon which saved 18.49 kWh as an annual gain of electrical energy.

Automated summary

A night radiative cooling technology is proposed in this study to passively solve the thermal problem caused by solar radiation absorbed by photovoltaic thermal systems but not transformed into electricity. By cooling the system water at night and using it for cooling the photovoltaic cells the next day, the proposed method reduces the daily temperature of the cells and improves their monthly gain of electrical energy compared to conventional methods.