Radiative cooling of solar cells with micro-grating photonic cooler

Radiative cooling of solar cells has been proposed in recent years and has elicited much interest from fields of materials science to engineering science. Herein, a silica micro-grating photonic cooler is proposed, designed, and fabricated to radiatively cool solar cells. It is shown that the micro-grating silica can not only improve the thermal emissivity of the bulk silica to over 0.9 required for enhanced radiative cooling of solar cells but also exhibits a slight anti-reflection effect for sunlight. The outdoor experiment demonstrates that the proposed cooler can passively reduce the temperature of the commercial silicon cell by 3.6 °C when applied on the top of the cell under solar irradiance range from approximately 830 W m −2 to 990 W m −2 , even though the cell already possesses a strong thermal emissivity of 0.67 and such a cooler slightly enhance the light trapping effect of the cell. This work provides an alternative way to design the solar-transparent infrared-emissive cooler for enhanced radiative cooling of solar cells and shows its cooling potential. • A silica micro-grating photonic cooler is proposed to radiatively cool solar cells. • Grating silica exhibits emissivity over 0.9 and simultaneously has anti-reflection effect for sunlight. • A temperature reduction of 3.6 °C is realized for the commercial solar cell with the grating silica.