Thermal and electrical characterization of catastrophic degradation of silicon solar cells submitted to reverse current stress

With this paper we present an extensive analysis of the degradation of Si-based solar cells submitted to reverse-bias stress. The study was carried out by combined electrical, electro-optical and thermal measurements, executed at the different stages of the stress tests. Results indicate that exposure to reverse bias may induce severe modifications of the shunt resistance, due to modifications in the parasitic leakage paths which can be revealed as hot spots by infrared thermal imaging. I-V measurements carried out at different illumination levels provide information on the efficiency and fill factor modifications induced by the decrease in shunt resistance. Finally the modifications in the electrical characteristics of the cells are simulated and fitted by a two-diode model.