Irradiance-dependent current-limiting behavior of multijunction solar cells

Measurements of tandem GaInAsP/InGaAs concentrator solar cells are presented and demonstrate how the short-circuit current of multijunction cells can shift from the higher-current subcell to the lower-current subcell as irradiance increases. Basic modeling shows how this can occur for cells that exhibit a noticeably non-zero slope in the low-voltage regime of the current-voltage curve of the current-limiting subcell. This observation should be general to all series-connected multijunction cells of this nature.