Space solar cells go to work on earth

Multi-junction solar cells based on gallium arsenide are the most efficient photovoltaics devised to date: different layers are placed on top of one another, each one tuned to absorb different segments of the overall light spectrum. Developed for space, these high-efficiency solar cells have been adapted for use in terrestrial solar plants with concentrator systems to reflect and focus incoming sunlight. Today, they are in use in some 20 plants across four continents. They were adapted by Germany’s Fraunhofer Institute and Azur Space under ESA contract. Future research will quantify these cells’ longterm terrestrial reliability.