Enhancing radiative cooling performance for bifacial photovoltaic module using two kinds of polycarbonate films

Abstract. Radiative cooling, as a cooling method that does not consume any energy during operation, has become a hot topic in recent years. Unlike passive daytime radiative cooling in buildings, radiative coolers used in photovoltaic modules must also have high light transmittance, which undoubtedly makes relevant research more difficult. Currently, bifacial photovoltaic modules are widely available on the market, if traditional cooling methods are employed in the back of them, including passive cooling such as heat sink and active cooling such as air cooling and water cooling, it will block the rear irradiance into the module. Hence, radiative cooling is an excellent solution. In this paper, polycarbonate (PC) film and one composed with a high reflective layer are proposed. The former has high emissivity in the atmospheric window and the latter has high reflectivity in the near-infrared band. Both achieve a good cooling effect without affecting the normal operation of the module. We also prepared the reflective film on PC by magnetron sputtering, and its optical characteristics were also measured and compared with simulation results. We innovatively use PC material and combine the reflective film with quite simple structure. Compared with other research results, they are simpler and stabler film structures and have the advantages of low cost, easy installation, good cooling effect, and can be directly pasted on the surface of the photovoltaic module. It turns out that the cooling effect can reach 6.02°C with R-PC film and photoelectric conversion efficiency can be improved by 0.27% with PC film when hc  =  20  W  ·  m  −  2  ·  K  −  1 and Ta  =  27  °  C. Given its excellent performance, they have a broad application prospect in the daytime passive radiative cooling of bifacial photovoltaic modules.