New methods for measuring performance of monolithic multi-junction solar cells

The commercialization of multi-junction solar cells for both space and terrestrial applications has increased the need to accurately determine cell performance using typical solar simulators and test equipment. This paper describes specific test methods recently applied in characterizing the performance of both tandem and triple-junction solar cells. Methods applied included: current-voltage measurements in forward and reverse bias using a xenon-arc solar simulator; absolute spectral response measurements of separate junctions using both light and voltage bias; a device simulation model; and a spectral mismatch calculation procedure tailored to multi-junction cells. Procedures are illustrated using measurements for GaInP-GaAs tandem cells, GaInP-GaAs-Ge triple-junction cells, and Ge cells supplied by different manufacturers.