Japanese R&D activities of multi-junction and concentrator solar cells

Abstract

Japanese R&D activities of concentrator solar cells and systems are overviewed. Japan Energy developed high efficiency (31.7 % at 1-sun AM1.5G) InGaP/InGaAs/Ge 3-junction cell under support by NEDO (New Energy and Industrial Technology Development Organization) in addition to the world-record efficiency InGaP/GaAs//InGaAs 3-junction cell (33.3% at 1-sun AM1.5G) by Japan Energy, Sumitomo and TTI. This project is now taken over by Sharp and targeted to concentration application also supported by NEDO. The new target is 40 % efficiency under 500-sun concentration by March 2006. The SPFG (Single and non-alignment Photolithography Fine Grid) silicon cell is developed by TTI. The first prototype of non-imaging Fresnel lens, which expands acceptance half angle to 2/spl deg//12/spl deg/ and enabled low cost axis tracker was fabricated and tested by TUAT. The module with this nonimaging lens and the SPFG cell is now assembled and subjected to be tested.