Radiative cooling of solar cells with scalable and high-performance nanoporous anodic aluminum oxide

Photovoltaic performance can be efficiently enhanced by improving the transmittance of solar cell cover, but the heating from unavailable solar irradiation has significantly adverse impact on both efficiency and reliability of solar cells. Radiative cooling can passively dissipate heat to the cold space (∼3 K) through the atmospheric window (8–13 μm). In this work, we reported a high-performance and scalable radiative cooler for solar cells using nanoporous anodic aluminum oxide (AAO). More specifically, the fabricated AAO cooler exhibited a near-unity infrared (IR) emissivity of ∼0.97 (weighted with the IR emission intensity of 298 K blackbody) in the atmosphere window, while maintaining an excellent solar transmittance over 0.94. Moreover, radiative cooling experiments showed that the porous cooler can cool bare silicon wafer by ∼7.5 K under a solar irradiation of ∼850 W/m2 in humid areas (humidity ∼70%). More importantly, concentrating the solar irradiation of ∼554 W/m2 with 50 times Fresnel lens, the cooler can achieve a maximum temperature drop of ∼35.6 K without wind cover even in a cloudy day. To further reveal the practicality of proposed AAO cooler, performance modeling of single-junction crystalline silicon (c-Si) solar cell encapsulated with the AAO cooler has been developed. Compared with commercial solar cells, the improved annual output electricity of the solar cell with AAO cooler can reach ∼16.5 kW h/(a∙m2).