Investigation of the Impact of Illumination on the Polarization-Type Potential-Induced Degradation of Crystalline Silicon Photovoltaic Modules

Accelerated potential-induced degradation (PID) testing of photovoltaic modules is conventionally conducted in the dark and at high temperature and humidity levels without considering the influence of illumination. This study investigates the impact of illumination on the polarization-type PID (PID-p) on two different types of encapsulated (glass/backsheet) crystalline silicon solar cells: 1) n-type bifacial passivated emitter rear totally diffused (the front side is facing glass and PID-stressed); and 2) p-type bifacial passivated emitter and rear cell (the rear side is facing glass and PID-stressed). The samples are stressed under the conditions of -1000 V, 40 °C, and 40% relative humidity and at different irradiance levels (xenon lamps). While the type-A modules show no reduction in PID-p sensitivity under illumination up to 800 W/m², PID-p in the type-B modules is arrested by the light at an irradiance level as low as 10 W/m². Furthermore, PID-degraded type-B modules (degradation induced in the dark) exhibit a rapid recovery (full recovery in 20 min) upon exposure to light (40 W/m²). External quantum efficiency measurements on the type-B modules show that ultraviolet from 300 to 400 nm is mainly responsible for the fast recovery.