Production and development activities in multijunction solar cells for concentrator photovoltaics

Multijunction concentrator GaInP/GaAs/Ge cells are now manufactured on a large scale with typical production cell efficiencies of 37% at 500 suns. These cells are enabling concentrator system manufacturers to produce installations of high specific efficiency, competitive with other solar technologies and offering potentials for cost advantage in the future. Relying on years of space manufacturing experience and recognizing the difference between space and terrestrial solar cell manufacturing, Spectrolab is addressing issues of production scale up, developing the necessary manufacturing infrastructure and process control capabilities. Stringent qualification regiment, similar to that of space cells, is applied to assure long term quality. Spectrolab is also continuing the process of increasing the efficiency of concentrator cells beyond recently demonstrated 40.7%. The development activities includes optimization work to further improve three junction devices for near term introduction, as well as longer term research involving bandgap engineered cells with three and more junctions.