Japanese space solar cell activities-GaAs and Si

This paper describes Japanese space solar cell activities using GaAs and Si materials. First, we review GaAs solar cell performance, design, fabrication and flight data of Japanese domestic Communications Satellite-3 (CS-3). We introduce a Japanese satellite called COMETS (Communications and Broadcasting Engineering Test Satellite) using GaAs solar cells. Secondly, we review Si solar cell performance, design, fabrication, and discuss a high efficiency Si solar cell which has a 100 /spl mu/m nonreflective surface (NRS)/local back surface field (LBSF) and average efficiency of 18% at AMO conditions. Thirdly, we analyze flight data of a solar cell monitor (SCM) on Engineering Test Satellite-V (ETS-V). Through collecting the SCM data, we observed degradation phenomenon, due to solar flares which occurred in October 1989.