Modeling Moisture Ingress Through Polyisobutylene-Based Edge-Seals

Michael D. Kempe, Dhananjay Panchagade, Matthew O. Reese, Arrelaine A. Dameron

Research output: Contribution to journalArticlepeer-review

40 Scopus Citations


Photovoltaic devices are often sensitive to moisture and must be packaged in such a way as to limit moisture ingress for 25-years or more. Typically, this is accomplished through the use of impermeable front and backsheets (e.g., glass sheets or metal foils). However, this will still allow moisture ingress between the sheets from the edges. Attempts to hermetically seal with a glass frit or similarly welded bonds at the edge have had problems with costs and mechanical strength. Because of this, low diffusivity polyisobutylene materials filled with desiccant are typically used. Although it is well known that these materials will substantially delay moisture ingress, correlating that to outdoor exposure has been difficult. Here, we use moisture ingress measurements at different temperatures and relative humidities to find fit parameters for a moisture ingress model for an edge-seal material. Then, using meteorological data, a finite element model is used to predict the moisture ingress profiles for hypothetical modules deployed in different climates and mounting conditions, assuming no change in properties of the edge-seal as a function of aging.

Original languageAmerican English
Pages (from-to)570-581
Number of pages12
JournalProgress in Photovoltaics: Research and Applications
Issue number5
StatePublished - 2015

Bibliographical note

Publisher Copyright:
Copyright © 2014 John Wiley & Sons, Ltd.

NREL Publication Number

  • NREL/JA-5J00-57219


  • desiccant
  • diffusivity
  • edge-seal
  • humidity
  • modeling
  • moisture
  • photovoltaic
  • polyisobutylene


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