Theoretical analysis of solar cell performance assisted by passive cooling

Passive cooling strategies, such as radiative cooling and evaporation cooling, have attracted lots of interest in the heat dissipation of solar cells. However, how to evaluate the effect of these passive cooling strategies on the solar cell performance was lacking, which is critical for the passive cooling design of solar cells. In this work, an electricity-thermal model was built to discuss the solar cell performance under different passive cooling conditions. Compared with the common solar cell with a glass cover, the sky radiative cooling by improving mid-infrared thermal emittance or above-λg (effective cutoff wavelength) reflectance in the solar spectrum had a slight effect on the temperature drop or power improvement under natural convection. The core point was to ensure the near-perfect sub-λg transmittance using anti-reflection coatings, which played the main role in the solar cell performance. A low cell temperature did not mean a high cell outpower under the selective spectral cover, and the sub-λg transmittance could not be suppressed to improve heat dissipation performance. After introducing an evaporation cooling layer, the output power could be enhanced greatly, showing the wide adaptability to cool the solar cell with little effect on solar-to-electricity conversion efficiency in sub-λg spectra. These results could guide subsequent cooling structure design by integrating different cooling strategies to achieve a near-perfect passive cooling system.