A new mc-Si degradation effect called LeTID

Abstract

A new degradation mechanism (LeTID, Light and elevated Temperature Induced Degradation) for multicrystalline solar cells is presented. The degradation reaches relative power losses of up to 10% on a time scale of several hundreds of hours of carrier injection and at field relevant temperatures. LeTID leads to a highly injection dependent lifetime characteristic after degradation and features a regeneration phase. Characteristics of LeTID as a function of temperature and injection level are presented and a comparison between laboratory and outdoor tests is drawn. LeTID is significantly reduced by adapting the cell process and processing sequence.