Evolution of Multijunction Solar Cell Technology for Concentrating Photovoltaics

Multijunction solar cells have evolved from their original development for space missions to displace silicon cells in high concentrating photovoltaic (CPV) systems. Today's three-junction lattice-matched production cells have efficiency of 39–39.5% under high concentration, and there appears to be little opportunity for further efficiency gain with this three-junction technology. Future generations of CPV cells will exploit more than three junctions, with metamorphic subcells, or both technical approaches to achieve efficiencies >45%. As new designs seek closer current matching and further spectral splitting, atmospheric variability will necessitate careful modeling to optimize energy output. These new cells will also be higher cost, which will favor higher CPV system concentration.