Technology and Climate Trends in PV Module Degradation (Presentation): NREL (National Renewable Energy Laboratory)

Research output: NRELPresentation


To sustain the commercial success of photovoltaic (PV) technology it is vital to know how power output decreases with time. Unfortunately, it can take years to accurately measure the long-term degradation of new products, but past experience on older products can provide a basis for prediction of degradation rates of new products. An extensive search resulted in more than 2000 reporteddegradation rates with more than 1100 reported rates that include some or all IV parameters. In this presentation we discuss how the details of the degradation data give clues about the degradation mechanisms and how they depend on technology and climate zones as well as how they affect current and voltage differently. The largest contributor to maximum power decline for crystalline Sitechnologies is short circuit current (or maximum current) degradation and to a lesser degree loss in fill factor. Thin-film technologies are characterized by a much higher contribution from fill factor particularly for humid climates. Crystalline Si technologies in hot & humid climates also display a higher probability to show a mixture of losses (not just short circuit current losses) comparedto other climates. The distribution for the module I-V parameters (electrical mismatch) was found to change with field exposure. The distributions not only widened but also developed a tail at the lower end, skewing the distribution.
Original languageAmerican English
Number of pages53
StatePublished - 2012

Publication series

NamePresented at the 27th European PV Solar Energy Conference, 24-28 September 2012, Frankfurt, Germany

NREL Publication Number

  • NREL/PR-5200-56690


  • degradation rates
  • field testing
  • mismatch
  • performance
  • photovoltaic systems
  • PV module


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