High-efficiency GaInP/GaAs tandem solar cells for space and terrestrial applications

GaInP/GaAs tandem solar cells are proving to be a highly adaptable, high efficiency photovoltaic technology. GaInP/GaAs tandem cells have now exceeded all confirmed two-terminal efficiencies for cells of any material combination at one-sun air-mass 1.5 global (AM1.5G) with an efficiency η=29.5%, at 160-suns AM1.5 direct (AM 1.5D) with η=30.2%, at one-sun AMO with η=25.7%, and at AMO with η=19.6% after 1-MeV, 10¹⁵-cm^-2 electron irradiation. These high efficiencies reduce the balance-of-system costs for a photovoltaic power system relative to a system using less efficient cells. This balance-of-system leverage has made this technology competitive in the near term for space and concentrator terrestrial applications even through the GaInP/GaAs cells are relatively expensive. A starting point for these high efficiencies is the high quality of the single-crystal epitaxial material. Recent advances are attributed to improvements in interface passivation layers and cell designs