Reverse Bias and Reverse Currents in CIGS Thin Film Solar Cells and Modules

摘要

Reverse IV-characteristics of CIGS based solar cells have an impact on the reliability of these devices as during shadowing of single cells in a module a high reverse bias can develop leading possibly to a junction damage and hot spots. In this study the reverse current characteristics of highly efficient solar cells and integrated modules were investigated and correlated to the occurrence of metastabilities of these thin film solar cells. The reverse IV-characteristics can be modelled by a reverse diode which limits the bias during shadowing of single devices. By optimization of the operating conditions this reverse bias can be minimized. Modelling of the junction characteristics indicates that interface properties are responsible for the measured reverse currents.