Investigation of Potential-Induced Degradation in Bifacial n-PERL Modules

A potential-induced degradation (PID) test method for bifacial double-glass silicon modules is first recommended for studying PID effects at the particular side of interest (the front or rear). This could be achieved by maintaining the same electric potential between solar cells and the untargeted module surface. Using the recommended test method, PID effects on the rear of n-type bifacial passivated emitter rear locally-diffused (bifacial n-PERL) devices (n-base passivated with silicon nitride) are studied. The rear of the n-PERL modules exhibits excellent stability under negative-bias conditions (relative to the ground). However, a huge power loss is observed when they are stressed with + 1000 V, likely due to PID-polarization occurring at the rear. The PID damage is recoverable by illuminating the rear module surface with artificial light. Most of the power loss can even be regenerated by several flashes on the module rear side from a solar simulator.