Sharp III-V solar cell equals conversion efficiency record of 43.5%
Sharp has achieved what it claims is the world’s highest solar cell conversion efficiency of 43.5% using a concentrator triple-junction compound semiconductor solar cell. The result is reported for May 30th, 2012, for concentrator solar cells at the research level, based on a survey by Sharp. The conversion efficiency was confirmed by the Fraunhofer Institute for Solar Energy (ISE) in April 2012 under a light-concentrating magnification of 306 times. With a cell surface of approximately 0.167 cm2, the conversion efficiency is the same as that achieved by U.S. firm Solar Junction in March 2011. These III-V based solar cells are used in a lens-based concentrator system that focuses sunlight on the cells to generate electricity. Sharp's concentrated triple-junction compound semiconductor solar cell with conversion efficiency of 43.5% Compound solar cells utilise photo-absorption layers made from compounds consisting of two or more elements, such as indium and gallium. The basic structure of this latest triple-junction compound solar cell uses Sharp’s proprietary technology that enables efficient stacking of the three photo-absorption layers, with InGaAs as the bottom layer. To achieve this latest increase in conversion efficiency, Sharp capitalised on the ability of this cell to efficiently convert sunlight collected via three photo-absorption layers into electricity. The firm also optimised the spacing between electrodes on the surface of the concentrator cell and minimised the cell’s electrical resistance. This latest Sharp breakthrough came about through research and development efforts that are part of the “R&D on Innovative Solar Cells” project promoted by Japan’s New Energy and Industrial Technology Development Organisation (NEDO). NEDO is one of Japan’s largest public management organisations for promoting research and development as well as for disseminating industrial, energy, and environmental technologies. ISE also participates on this project. Their superior conversion efficiency make compound solar cells ideal for use in space satellites, which is their primary application. Sharp’s aim for the future is to apply this latest development success into concentrator photovoltaic power systems that can efficiently generate electricity using small-surface-area solar cells and make them practical for terrestrial use.