Quick test for reversible and irreversible PID of bifacial PERC solar cells

Abstract High voltage stress at the rear side of bifacial PERC cells leads to severe power losses. In contrast to monofacial PERC solar cells, reversible de-polarization related potential induced degradation (PID-p) and irreversible corrosive potential induced degradation (PID-c) can occur. Our results show that a reliable assessment of the solar cells power losses requires a modified PID test method which includes illumination in addition to the high voltage stress test. Furthermore, a recovery step needs to be added to the test scheme to separate reversible PID-p contributions from irreversible PID-c damages. We show that both, the degree of degradation as well as the contributions of PID-p and PIC-c depend sensitively on the solar cell under consideration. Thus, we propose to include both illumination during PID stress as well as a recovery step in the PID test scheme for bifacial PERC cells. Additionally, we show that the most sensitive cell parameter for the detection of rear side PID is given by the rear side measurement of the short circuit current. Finally, we present results showing that a 0.1 sun illumination during this characterization step is sufficient for an assessment of the PID. Based on these results, we propose a test setup which combines the required stress test conditions with an in-situ tracking of the PID.