Potential induced degradation of N-type bifacial silicon solar cells: An investigation based on electrical and optical measurements

Abstract

This paper reports an extensive analysis of the potential-induced degradation (PID) of N-type bifacial solar cells. The analysis is based on combined electrical characterization, electroluminescence and external quantum efficiency measurements, carried out on solar cells submitted to high PID stresses. We investigate the impact of two different encapsulation materials: (i) polyolefin elastomer (POE) and (ii) ethylene-vinyl-acetate (EVA). We describe the degradation and recovery kinetics as a function of the temperature and the stress voltage. Moreover we demonstrate that the POE can be adopted to reduce the decrease of conversion efficiency during PID stresses. Finally we investigate the effects of PID with an optical analysis in order to find the main cause of the performance degradation.