A Theoretical Analysis on the Energy Production of III-V Multi-Junction Solar Cells under Realistic Spectral Conditions

Abstract

In this paper we present a methodology which uses the detailed balance method to determine the optimum bandgap combination of III-V triple-junction solar cells for the highest yearly energy production. As an example for the methodology we analyse two geographical locations on Earth with distinct spectral conditions. For these places the monthly average of the measured aerosol optical depth and the precipitable water are used to calculate direct solar spectra with a discretisation of one spectrum per hour. The model is used to analyse the spectral sensitivity of the bandgap design of four practical III-V triple-junction solar cell structures. In addition, the impact of the designated operating temperature is investigated. Furthermore, the ideal bandgap combination for a maximal energy harvest is calculated for each location. It is shown that structures optimized for the standard AM1.5d reference spectrum yield nearly optimal energy harvesting efficiencies at geographical locations with red-rich spectral conditions. However, the choice of the right bandgap combination is essential. By contrast, structures should be re-optimized for locations with a high share of blue light.