Changes in characteristics during storage of CIS-type solar modules

We investigated the unevenness of, and change in, the characteristics of CIS-type thin-film solar modules during a 6-month storage period. The maximum output power (Pmax) improved by an average of 1.72% in that time. This improvement was attributable mainly to the increase in short-circuit current (Isc), which was about 5.9% after 6 months. The change in Pmax also depended on the change in the fill factor (FF); the correlation coefficient between Pmax and FF was 0.68. Finally, as Pmax was the main factor in module performance, its change also depended on both the value of, and change in, series resistance over time.