Investigation on light elevated temperature-induced degradation of PERC PV modules

This study aims to understand LeTID over multiple cycles of the LeTID stress test (13 cycles) by applying IEC TS 63342:2022 to commercial polycrystalline and monocrystalline silicon PERC modules. Under STC, after four LeTID test cycles, the maximum power reduction observed for polycrystalline and monocrystalline silicon PERC modules was 2.5% and 2.3%, respectively. After four weeks, the performance of the polycrystalline silicon technology improved, while that of the monocrystalline silicon technology performance continues to decline at a slower rate. Performance reduction was primarily attributed to changes in current, rather than voltage. Furthermore, under low irradiation conditions, evidence indicates that both types of PERC modules respond effectively throughout the 13 LeTID test cycles. EL imaging, utilizing grayscale image processing, was used to compare LeTID test results from cycles 1 to 4 (degradation phase) and cycle 10 (regeneration-like phase). Peak pixel distribution values indicate PV module brightness areas under different current injection levels, including Isc and 0.1xIsc.