Performance of CPV modules based on vertical multi-junction cells under non-uniform illumination

Abstract

High-voltage silicon Vertical Multi-Junction (VMJ) cells can accept high concentration with peak efficiency potentially reaching close to 30%. Dense-array modules with high-voltage cells should allow a parallel connection with voltage matching rather than series connection with current matching, leading to lower mismatch losses under non-uniform illumination. The performance of a dense array with VMJ cells connected in parallel under non-uniform illumination is investigated, in comparison to a module with conventional cells connected in series. The incident flux distribution corresponds to that of a parabolic dish with and without a homogenizer. The number of junctions in each VMJ cell is a free parameter for optimization. The results show a clear advantage of the VMJ module over the conventional module under non-uniform illumination, allowing reduction or even elimination of homogenizing secondary optics, and easing the tracking accuracy requirements.