Global acceleration factors for damp heat tests of PV modules

Time-to-failure data from PV modules subjected to damp heat tests of different temperature and relative humidity conditions was compiled from SunEdison and literature reports. Analysis of the data led to a power law model of time-to-failure for PV modules in damp heat conditions as follows: TTF = A * e^(Ea/kT) * RH^ (n), where TTF is the time in hours to reach 20% module power loss, A = 6.4e-10, Ea = 0.89 ± 0.11 eV, and n = -2.2 ± 0.8. Damp heat acceleration factors were then computed for >2500 global typical meteorological year data sets with reference to the standard 85°C and 85% relative humidity test condition. The distribution of damp heat acceleration factors for the United States, Europe, China and India reflect the importance of regional climate on predictions of long-term PV module reliability.