Seasonal heat regulation in photovoltaic/thermal collectors with switchable backplate technology: Experiments and simulations

Photovoltaic/thermal (PV/T) collectors can simultaneously generate electrical and thermal energy, but the overheating phenomenon often occurs in hot seasons, leading to poor electrical performance and shortened lifetime in PV modules. In this study, a thermal regulation strategy by switching the backplate is introduced into the conventional PV/T collector, which can adapt to different heat demands in different seasons by opening or closing the backplate, achieving better electrical performance in summer without affecting winter heating. Comparative experiments between the switchable and conventional PV/T collectors are conducted to observe the performance advantage. The results show that the maximum stagnation temperature of the switchable PV/T collector is 18.1 °C lower than the conventional one, which relatively improves electrical efficiency by 8.6%. Subsequently, an annual performance prediction by a validated mathematical model illustrates that the thermal performance of the switchable PV/T collector in the heating season is comparable to the conventional PV/T collector, but the electrical efficiency can be increased by 6.26% in the non-heating season. Moreover, further study shows the proposed strategy has efficient regulation in other types of PV/T collectors similarly, demonstrating the positive role of switchable backplate technology in enhancing electrical efficiency and addressing the seasonal contradiction in PV/T collector operation.