Moisture Ingress Prediction in Polyisobutylene-Based Edge Seal with Molecular Sieve Desiccant

Michael D. Kempe, Dylan L. Nobles, Lori Postak, Jose Alonzo Calderon

Research output: Contribution to journalArticlepeer-review

15 Scopus Citations


Often photovoltaic modules are constructed with materials that are sensitive to water. This is most often the case with thin film technologies, including perovskite cells, where the active layers are a few microns thick and can be sensitive to moisture, liquid water or both. When moisture or liquid water can ingress, a small amount of water can lead to corrosion and depending on the resulting reactions, a larger local detrimental effect is possible. To prevent moisture from contacting photovoltaic components, impermeable frontsheets and backsheets are used with a polyisobutylene (PIB)-based edge seal material around the perimeter. Here, we evaluate the ability of a PIB-based edge seal using a molecular sieve desiccant to keep moisture out for the expected module lifetime. Moisture ingress is evaluated using test coupons where the edge seal is placed between 2 pieces of glass, one of which has a metallic calcium film on it, and monitoring the moisture ingress distance as a function of time. We expose samples to different temperature and humidity conditions to create permeation models useful for extrapolation to field use. This extrapolation indicates that this PIB material is capable of keeping moisture out of a module for the desired lifetime.

Original languageAmerican English
Pages (from-to)93-101
Number of pages9
JournalProgress in Photovoltaics: Research and Applications
Issue number2
StatePublished - 2018

Bibliographical note

Publisher Copyright:
Copyright © 2017 John Wiley & Sons, Ltd.

NREL Publication Number

  • NREL/JA-5J00-68790


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


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