Effect of light degradation on bifacial Si solar cells

We fabricated bifacial-type rear-floating-emitter solar cells and triode so lar cells from several types of wafers and investigated the light degradati on of solar-cell performance. Rear efficiency of a rear-floating-emitter bi facial solar cell degrades in proportion to bulk-minority carrier lifetime, This degradation of cell efficiency is much larger than that reported so f ar. Bifacial cells must therefore be made from wafers that are not degraded by light. And it was found that magnetic-foeld-applied CZ wafers or galliu m-doped CZ wafers meet this requirement very well. Three-terminal measureme nt showed that light degradation does not have much influence on rear effic iency of triode cells compared with that of two-terminal bifacial cells. (C ) 2001 Elsevier Science B.V. All rights reserved.