Thin-film reliability trends toward improved stability

Long-term, stable performance of photovoltaic (PV) modules will be increasingly important to their successful penetration of the power grid. This paper summarizes more than 150 thin-film and more than 1700 silicon PV degradation rates (R
_d
) quoted in publications for locations worldwide. Partitioning the literature results by technology and date of installation statistical analysis shows an improvement in degradation rate especially for thin-film technologies in the last decade. A CIGS array deployed at NREL for more than 5 years that appears to be stable supports the literature trends. Indoor and outdoor data indicate undetectable change in performance (0.2±0.2 %/yr). One module shows signs of slight degradation from what appears to be an initial manufacturing defect, however it has not affected the overall system performance.