Energy Yield Limits for Single-Junction Solar Cells

Energy yield'' is a key performance metric that describes generated electricity (kWh) in a realistic operating environment, with significance beyond that of the lab-measured power conversion efficiency. Herein, we present fundamental energy yield limits based on 2015 global satellite data for solar cells with various band-gaps, including established technologies such as Si and CdTe and emerging materials such as perovskites. Based on an adapted detailed-balance model with experimental validation, we derive an empirical relation that allows approximating harvesting efficiencies from standard testing condition efficiencies. This equation provides a straightforward way to calculate energy yield for any new technology and enables a fair comparison of lab-measured devices with different band-gaps. We find that the ideal band-gap for maximizing energy yield is 1.35 eV. We show that harvesting efficiencies correlate with Koppen-Geiger climate zones, which indicates that results obtained in a given climate can be translated to other regions with similar climate.