Potential Induced Degradation Studies with high Temporal Resolution Reveal Changes of Field Effect Passivation States at the Rear Side of Bifacial Silicon Solar Cells

The rear side of bifacial silicon solar cells can suffer potential induced degradation (PID) when subject to high voltage stress. The PID of the polarization type (PID-p) has its largest impact on the rear side short circuit current and is attributed to loss of surface passivation. In this study, PID tests at bifacial silicon solar cells reveal fast transient changes of rear side short circuit current within minutes when subject to voltage stress at the rear. The short circuit current measured under rear side illumination first decreases significantly and increases subsequently reaching almost the level of the initial state. This effect can be explained by field-induced band banding near the rear surface.