Comparative analysis of switchable natural cooling methods for efficient thermal management in photovoltaic/thermal collectors

Photovoltaic/thermal (PV/T) collectors can produce heat and electricity simultaneously, but the overheating phenomenon also occurs on hot days, significantly compromising their performance and lifetime. To address this issue, this study suggests incorporating switchable heat dissipation modes into conventional PV/T collectors to enhance thermal management ability. Such an approach allows for efficient heat collection when the thermal demand is high and timely heat dissipation during periods of low heat demand. In this paper, four types of PV/T collectors with different switchable heat dissipation configurations are introduced and analysed using validated two-dimensional steady-state mathematical models. The results demonstrate that, under a typical summer day in Hefei, the four switchable cooling modes can dramatically drop the stagnation temperature, ranging from 26.2 °C to 46.6 °C, thereby improving electrical efficiency by 2.22 % to 3.94 %. In addition, the regulation and cooling effect of the PV/T collector becomes more obvious as the ambient temperature increases and the solar irradiation becomes stronger. To illustrate performance differences, energy flow diagrams of each PV/T collector in heat dissipation modes are established, highlighting variations in solar energy conversion and heat dissipation effects. These findings provide critical insights for the future design of PV/T collectors with multi-mode operation and enhanced overheating protection functions.