Long-term performance analysis of copper indium gallium selenide thin-film photovoltaic modules

Current accelerated qualification tests of photovoltaic (PV) modules mostly assist in avoiding premature failures but can neither duplicate changes occurring in the field nor predict useful product lifetime. Therefore, outdoor monitoring of field-deployed thin-film PV modules was undertaken at FSEC with the goal of assessing their performance in hot and humid climate under high system-voltage operation. Significant and comparable degradation rate of -5.13 +/- 1.53% and -4.5 +/- 1.46% per year was found using PVUSA type regression analysis for the positive and negative strings, respectively of 40W glass-to-glass Cu-In-Ga-Se (CIGS) thin-film PV modules in the hot and humid climate of Florida. Using the current-voltage measurements, it was found that the performance degradation within the PV array was mainly due to a few (8% to 12%) modules that had substantially higher degradation. The remaining modules within the array continued to show reasonable performance ( \u3e 96% of the rated power after similar to four years)