Optical approaches for passive thermal management in c-Si photovoltaic modules

Abstract

Elevated operating temperatures of solar cells encapsulated in modules lead to reduced efficiency and module lifetime. Here, we provide a comprehensive overview of the challenges and opportunities for passive optical thermal management of PV modules based on the rejection of sub-band-gap light by idealized reflectors and scatterers applied at different interfaces within crystalline Si modules and discuss the limitations to performance at each interface. We find that the annual power-weighted average operating temperature is most readily reduced via sub-band-gap reflection from the module glass, by 3.3 K for Al-BSF modules and 2.9 K for PERC modules with 100% sub-band-gap reflection. Sub-band-gap reflection at the cell interface offers up to 2.2 K (1.8 K) temperature reduction for Al-BSF (PERC) modules, increased cell rear reflection offers up to 1.2 K temperature reduction, and directional scattering offers up to 1.5 K reduction. Guide for passive optical methods of cooling photovoltaic modules Outdoor simulation of PV modules with integrated sub-band-gap reflective mirrors Mirrors at outer glass or cell rear interface are most promising Calculation of effects of backscattering of sub-band-gap light within the module Slauch et al. provide an overview of opportunities for photovoltaic thermal management focused on the rejection of incident sub-band-gap light. They calculate reductions in waste heat generated and operating temperature via combined optical, electrical, and thermal module simulation under 1 year of realistic outdoor conditions. This method allows the determination of the limits of passive optical cooling as a function of the sub-band-gap reflectivity and the reflective interface.