Variability of LID regeneration at lower temperatures: case maritime climate

In this paper we report on the variability of light induced degradation and regeneration at lower sample temperatures than commonly used in literature. These temperatures are more relevant for maritime climates.Typically LeTID is investigated under laboratory conditions at temperatures between 80 and 140 ◦C. We subjected a group of samples to light intensities between 0.4 and 1 sun and temperatures of 50-70 ◦C, between the laboratory LeTID ranges and the temporary recovery range. We found that in such conditions the time to reach maximum degradation and complete regeneration is longer and the variability in these times is significantly increased. At 50 ◦C, we found significant longer timeframes for the degradation and regeneration cycle but no change in the maximum degradation amount compared to 70 ◦C. We constructed IV curves of modules by connecting in series the measured IV curves of LID exposed cells, with this large variability in degradation and regeneration behaviour. Simulated modules at lower temperature will exhibit degradation for longer than the average degradation time of the cells. Due to current matching of series connected cells, modules can be expected to have degradation and regeneration cycles which depend mostly on the slowest cell. The implication for outdoor deployment in a cool climate is that early stage yearly yield exceeds expectations, due to a delayed degradation profile, while the yearly yield in later years will be lower and for a longer time than would be expected for warmer, sunnier climate zones.