Degradation in PV Encapsulation Transmittance: An Interlaboratory Study Towards a Climate-Specific Test

David C. Miller, Eleonora Annigoni, Amal Ballion, Jayesh G. Bokria, Laura S. Bruckman, David M. Burns, Chen Xinxin, Lamont Elliott, Feng Jiangtao, Roger H. French, Sean Fowler, Gu Xiaohong, Peter L. Hacke, Christian C. Honeker, Michael D. Kempe, Hussam Khonkar, Michael Kohl, Laure Emmanuelle Perret-Aebi, Nancy H. Phillips, Kurt P. ScottFanny Sculati-Meillaud, Tsuyoshi Shioda, Shigeo Suga, Shin Watanabe, John H. Wohlgemuth

Research output: Contribution to conferencePaperpeer-review

24 Scopus Citations


Reduced optical transmittance of encapsulants resulting from ultraviolet (UV) degradation has frequently been identified as a cause of decreased PV module performance through the life of service in the field. The present module safety and qualification standards, however, apply short UV doses only capable of examining design robustness or infant mortality failures. Essential information that might be used to screen encapsulation through product lifetime remains unknown. For example, the relative efficacy of xenon-arc and UVA-340 fluorescent sources or the typical range of activation energy for degradation is not quantified. We have conducted an interlaboratory experiment to provide the understanding that will be used towards developing a climate- and configuration-specific (UV) weathering test. Five representative, known formulations of EVA were studied in addition to one TPU material. Replicate laminated silica/polymer/silica specimens are being examined at 14 institutions using a variety of indoor chambers (including Xenon, UVA-340, and metal-halide light sources) or field aging. The solar-weighted transmittance, yellowness index, and the UV cut-off wavelength, determined from the measured hemispherical transmittance, are examined to provide understanding and guidance for the UV light source (lamp type) and temperature used in accelerated UV aging tests.

Original languageAmerican English
Number of pages6
StatePublished - 14 Dec 2015
Event42nd IEEE Photovoltaic Specialist Conference, PVSC 2015 - New Orleans, United States
Duration: 14 Jun 201519 Jun 2015


Conference42nd IEEE Photovoltaic Specialist Conference, PVSC 2015
Country/TerritoryUnited States
CityNew Orleans

Bibliographical note

See NREL/CP-5J00-63508 for preprint

NREL Publication Number

  • NREL/CP-5J00-66364


  • durability
  • reliability
  • thermal activation


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