New Hampshire — Concentrating photovoltaic system manufacturer and solar developer Soitec, in conjunction with CEA-Leti both of France along with the Fraunhofer Institute for Solar Energy Systems ISE in Germany, announced that they have achieved a new world record for the direct conversion of sunlight into electricity.
The record multi-junction solar cell converts 46 percent of the solar light into electrical energy. Multi-junction cells are used in concentrator photovoltaic (CPV) systems to produce solar electricity in PV power plants, in regions with a large amount of direct solar radiation. Soitec is currently constructing a 44-MW CPV plant in Towsrivier, South Africa. The achievement of a new world record comes just one year after the one previously announced in September 2013 by these French and German partners.
Multi-junction solar cells are based on a selection of III-V compound semiconductor materials. The world record cell is a four-junction cell, and each of its sub-cells converts precisely one quarter of the incoming photons in the wavelength range between 300 and 1750 nm into electricity. When applied in concentrator PV, a very small cell is used with a Fresnel lens, which concentrates the sunlight onto the cell. The new record 46 percent efficiency was measured at a concentration of 508 suns and has been confirmed by the Japanese AIST (National Institute of Advanced Industrial Science and Technology).
One of the most difficult challenges that had to be met by this cell is the exact distribution of the photons among the four sub-cells, which was achieved through the precise tuning of the composition and thicknesses of each layer inside the cell structure.
Soitec plans to produce a 50 percent efficient cell in the near future and according to the company’s VP of Solar Cell Product Development Jocelyne Wasselin, this new achievement paves the way to do that. “I have no doubt that this successful cooperation with our French and German partners will drive further increase of CPV technology efficiency and competitiveness,” she said in a statement. Wasselin added that Soitec currently employs 25 engineers and technicians at its production line in France that uses bonding and layer-transfer technologies.
Lead image: New record solar cell on a 100 mm wafer yielding approximately 500 concentrator solar cell devices. ©Fraunhofer ISE/Photo Alexander Wekkeli