Multi-field coupling challenges the stability test of silicon solar cells

Abstract

UV-induced degradation is an important factor affecting the stability of silicon heterojunction (SHJ) solar cells. Many works investigated the root cause of this degradation previously, but its coupling with other external stress, such as temperature, has rarely been reported. Here, we examine the decrease in SHJ solar cells induced by UV irradiation at different temperatures (−30 and 80 °C) using ultraviolet lamps at 200 W/m2 for 300 h. The results showed that the UV-induced degradation is more severe at low temperature (−30 °C), leading to a significant power decrease (13.5% on average) compared with the power attenuation of the solar cell at 80 °C (1.59% on average). At a low temperature (−30 °C), the VOC and FF evidently decrease much faster. Light soaking can repair the damage to some extent, but the power conversion efficiency cannot restore to the initial value. A 3D microscope confirmed this is because the silver metal electrodes are permanently degraded. These findings challenge the standard International Electrotechnical Commission (IEC) stability test for solar cells, in other words, we have to take into account multi-field coupling to evaluate the long-term reliability of solar cells in real environments.