Topcon Solar Modules

UV Degradation in Lab and Field Conditions

Abstract

The UV degradation of TOPCon solar modules with different material compositions (BOM) was investigated and correlated in both field studies and accelerated aging laboratory tests. A UV treatment with 120 kWh/m² leads to significant power losses ranging from 1.3% to 13.7%, indicating a strong dependence on the specific material composition. Furthermore, it was found that additional degradation occurs beyond 120 kWh/m². Electroluminescence images (EL images) of laboratory UV-degraded modules show a characteristic checkerboard pattern indicative of UV-induced degradation (UVID). Additional degradation occurred during storage, which was partially reversible when the modules were re-irradiated.

After nine months in a ground-mounted system in Forst/Brandenburg, power losses of up to 2.4% were detected. Notably, this degradation was slightly lower than expected from UV-induced degradation tests (UVID) conducted in the laboratory. The EL images of field modules also displayed the characteristic checkerboard pattern, indicating that the UV degradation measured in the laboratory poses a real risk to the long-term stability of TOPCon modules in the field.

Due to the small number of modules examined, the statistical significance of the study is limited. Nevertheless, the results provide evidence of UV degradation of TOPCon modules under field conditions.