Chemical and Mechanical Interfacial Degradation in Bifacial Glass/Glass and Glass/Transparent Backsheet Photovoltaic Modules

Laura Spinella, Sona Ulicna, Archana Sinha, Dana Sulas-Kern, Michael Owen-Bellini, Steve Johnston, Laura Schelhas

Research output: Contribution to journalArticlepeer-review

10 Scopus Citations


Glass/glass (G/G) photovoltaic modules are quickly rising in popularity, but the durability of modern G/G packaging has not yet been established. In this work, we examine the interfacial degradation modes in G/G and glass/transparent backsheet modules under damp heat (DH) with and without system bias voltage, comparing emerging polyolefin elastomer (POE) and industry-standard poly(ethylene-co-vinyl acetate) (EVA) encapsulants. We investigate the transport of ionic species at cell/encapsulant interfaces, demonstrating that POE limits both sodium and silver ion migration compared with EVA. Changes to the chemical structures of the encapsulants at the cell/encapsulant interfaces demonstrate that both POE and EVA are more susceptible to degradation in modules with a transparent backsheet than in the G/G configuration. Adhesion testing reveals that POE and EVA have comparable critical debond energies after the DH exposures regardless of system bias polarity. The results of this study indicate that the interfacial degradation mechanisms of G/G appear to be similar to those of conventional glass/backsheet modules. For emerging materials, our results demonstrate that POE offers advantages over EVA but that transparent backsheets may accelerate encapsulant degradation due to increased moisture ingress when compared with the G/G structure.

Original languageAmerican English
Pages (from-to)1423-1432
Number of pages10
JournalProgress in Photovoltaics: Research and Applications
Issue number12
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.

NREL Publication Number

  • NREL/JA-5900-83343


  • adhesion
  • bifacial
  • DuraMAT
  • EVA
  • glass–glass
  • ion migration
  • POE


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