From sky back to sky: Embedded transparent cellulose membrane to improve the thermal performance of solar module by radiative cooling

Abstract

The actual high working temperature severely affects the performance of crystalline Si solar module, and cooling function is favorited. Here we made a wood-based cellulose membrane having good transparent, high emissivity in mid IR atmospheric window, it shows a radiative sky cooling ability. We investigate the membrane's porous and hierarchical morphology, transmission is averagely higher than 90% in solar spectra for composite of cellulose membrane, EVA and glass, the emissivity of cellulose membrane in 8–10 μm is larger than 0.9. Transparent cellulose membranes were prepared and embedded between solar cell and EVA for module encapsulation process. In the outdoor exposure experiment, we found that the cellulose membrane inside front of solar module can reduce the temperature of it, and around 2 °C cooling effect was obtained. Embedded cellulose membrane is simple, effective way to improve the thermal performance of solar module without weakening of solar spectra transmission and the performance. Keywords: Radiative cooling, Transparent cellulose membrane, Solar module, Thermal emissivity