Degradation of crystalline silicon solar cells caused by lightning induced impulse surge

Abstract

Crystalline silicon (c-Si) solar cells are connected in series to form Photovoltaic (PV) modules, which are installed at wide-open areas. They are exposed to lightning electromagnetic (EM) interference at high risk. The lightning EM field will induce an impulse surge in the loop of solar-cell string, and c-Si solar cells are prone to be damaged. To study the effect of lightning surge on monocrystalline silicon cells and polycrystalline silicon cells, the impulse voltage tests are conducted. The semiconductor structures of c-Si solar cells after test are observed using scanning electron microscopy (SEM). The results indicate that the lightning surge will generate some cracks and defects in the P-N junction. Under the strong electric field, the N-type emitter layer and the grain boundary could be destroyed, which contributes to the degradation of c-Si solar cell. Compared with the monocrystalline silicon cell, the polycrystalline silicon cell can withstand greater forward lightning surge, however, its maximum reverse lightning surge is relatively lower.