Testing dye-sensitized solar cells in harsh northern outdoor conditions

Here, we report on the behavior of dye solar cells in real-life weather conditions from a northern outdoor test covering for the first time cell performance measurements in harsh conditions with varying weather from mildly warm conditions to freezing and snowy. The effect of different weather conditions on the cell performance is quantitatively investigated by using correlations coefficients of weather parameters to cell performance. No degradation was observed during the frosty period, but instead during the warmer, rainy periods with high moisture levels. Nevertheless, after 6 weeks of outdoor testing in varying harsh conditions, the cells maintained on average 88% of their initial efficiency. Tracking the cell performance during the aging showed that the test cells generated roughly as much current at subzero temperatures as at warmer temperatures. Investigations of the degradation reactions revealed that while photoelectrode degradation was the main cause of degradation during this test, the loss of charge carriers, which had only a minor effect on performance during the test, would likely become a major degradation factor during the next 1000 h of testing. Furthermore, the test showed that the cells even doubled their efficiency in low light intensity conditions compared with the standard reporting conditions. Thus, the overall conversion efficiency during the whole experiment reached up to 50% higher values compared with the results in standard testing conditions.