Enhanced thermal performance of photovoltaic panels based on glass surface texturization

Abstract

Photovoltaic module temperature is a detrimental parameter influencing the energy yield and the durability of photovoltaic systems. Among the passive strategies to reduce the operating temperature of solar cells, radiative cooling is receiving a lot of attention, as an effective mean to passively evacuate heat in systems. The existence of a wavelength window of atmospheric transparency (8–13 μm) allows sending heat to outer space. The functionalization of the glass that could help to limit or reduce the temperature of the solar cells is an interesting approach. In this paper, we explore the effect of glass surface patterns in its radiation performance, so that the radiation cooling effect could be enhanced. The study is based on numerical simulations, calculating the spectral emissivity of different geometrical configurations of structures on top of the glass. Different geometrical figures of micrometers in size have been tested to find an optimal emissivity response in the transparent atmospheric window. Periodical patterns based on cones, pyramids, or moth-eye shapes result in emissivity responses close to one along thermal wavelengths (8–25 μm) which increases the emitted power of the glass. However, when assessing the cooling power under sunlight, the evaluation wavelength band has to be expanded (0.3–25 μm). Here, we found that not all geometrical figures are effective for radiative cooling. Surfaces textured by holes and pyramids show a substantial cooling effect, providing an increase in cooling power over the flat glass ranging from 40 W/m2 to 110 W/m2 depending on the temperature of the solar devices.