Prediction of Climate-Specific Degradation Rate for Photovoltaic Encapsulant Discoloration

Archana Sinha, Hamsini Gopalakrishna, Arun Subramaniyan, Dheepak Jain, Jaewon Oh, Dirk Jordan, GovinaSamy TamizhMani

Research output: Contribution to journalArticlepeer-review

21 Scopus Citations


Encapsulant discoloration is a well-known field degradation mode of crystalline-silicon photovoltaic modules, particularly in the hot climate zones. The discoloration rate is influenced by several weathering factors, such as UV light, module temperature, and humidity, as well as the permeability of oxygen into the module. In this article, a rate dependence model employing the modified Arrhenius equations to predict the degradation rate for encapsulant discoloration in different climates is presented. Two modeling approaches are introduced, which utilize the field and accelerated UV testing degradation data in conjunction with the field meteorological data to determine the acceleration factor for encapsulant browning. A novel method of accelerated UV stress testing at three simultaneous module temperatures in a single environmental chamber test run is implemented to estimate the activation energy for browning. The test was performed on three field-retrieved modules to capture the wear-out failure mechanism. The degradation in short-circuit current Isc rather than maximum power is used as a decisive parameter for the discoloration analysis. Furthermore, the developed model has been used to predict the Isc degradation rate for the Arizona field characterized by a hot and dry climate and is validated against the field-measured value. It has also been applied to other climate types, e.g., the cold and dry climate of New York.

Original languageAmerican English
Article number9093139
Pages (from-to)1093-1101
Number of pages9
JournalIEEE Journal of Photovoltaics
Issue number4
StatePublished - Jul 2020

Bibliographical note

Publisher Copyright:
© 2011-2012 IEEE.

NREL Publication Number

  • NREL/JA-5K00-77554


  • Acceleration factor (AF)
  • activation energy
  • Arrhenius model
  • degradation rate
  • discoloration
  • encapsulant
  • photovoltaic (PV) module


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