Comparative Analysis of Switchable Natural Cooling Methods for Efficient Thermal Management in Photovoltaic/Thermal Collectors

Abstract

Photovoltaic/thermal (PV/T) collectors can produce heat and electricity simultaneously, but the overheating phenomenon also occurs on hot days, which affects their performance and lifetime significantly. Therefore, incorporating switchable heat dissipation modes into conventional PV/T collectors can achieve the ability to both collect more heat when the thermal demand is high and dissipate the excess heat timely in low heat demand. In this paper, four types of PV/T collectors with different switchable heat dissipation configurations are proposed to enhance thermal regulation and optimize performance under varying thermal demands. The temperature regulation and performance of each configuration are analyzed and compared using validated two-dimensional steady-state mathematical models. The results demonstrate that, under a typical summer weather day in Hefei, the four switchable cooling modes can dramatically drop the stagnation temperature, ranging from 26.2°C to 46.6°C, 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. Finally, energy flow diagrams of each PV/T collector in heat dissipation modes are established to explore the performance differences in solar energy conversion and heat dissipation effects. These findings are essential for the future design of PV/T collectors with multi-mode operation and overheating protection functions.

Keywords: Photovoltaic/thermal (PV/T), solar energy, Thermal regulation, Convection heat loss, Heat dissipation