Outdoor Thermal Performance of Photovoltaic Devices with Enhanced Daytime Radiative Cooling Glass

The increase in the operating temperature decreases the efficiency and the lifetime of photovoltaic (PV) systems. Radiative cooling effect offers a promising solution to passively reduce the operating temperature of PV modules using the atmospheric window (AW). Glass is a well-known material used as front cover of PV modules. It presents a fairly good emissivity in the AW although a low-absorption resonance at 9-10 mu m decreases its overall emissivity, hampering its radiative cooling capacity. This effect can be reduced by tailoring the glass surface. Herein, glass samples are microstructured and characterized obtaining a decrease in reflectance and a substantial increase of the emissivity in the AW. Next, the glass samples are laminated with solar cells and installed outdoors without any convection barrier and monitored in open-circuit configuration for almost half a year. The days are sorted by three meteorological conditions: sunny, partly cloudy, and cloudy days, which correspond to a decreasing availability of the AW. The average temperature difference between two samples is 0.8, 0.7, and 0.1 degrees C for the sunny, partly cloudy, and cloudy days, respectively. The maximum temperature difference obtained is 2.0 degrees C. No correlation between temperature difference and wind speed is observed.

Automated summary

Radiative cooling effect can passively reduce the operating temperature of photovoltaic (PV) systems by utilizing the atmospheric window. The emissivity of glass in the atmospheric window can be improved by microstructuring the glass surface, enhancing its radiative cooling capacity. Experimental results show that the temperature difference between glass samples and solar cells ranges from 0.1 to 2.0 degrees Celsius under different meteorological conditions, and there is no correlation between temperature difference and wind speed.