Evaluation of Encapsulant Adhesion to Surface Metallization of Photovoltaic Cells: Preprint

Nicholas Bosco, Jared Tracy, Reinhold Dauskardt

Research output: Contribution to conferencePaper

Abstract

Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of EVA encapsulant to screen printed silver metallization was evaluated. At room temperature, the fracture energy, Gc [J/m2], of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/AR coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 hours of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2, while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and elevated temperature, and may explain the propensity for delamination to occur at metallized surfaces in the field.
Original languageAmerican English
Number of pages5
StatePublished - 2017
Event2017 IEEE 44th Photovoltaic Specialists Conference (PVSC) - Washington, D.C.
Duration: 25 Jun 201730 Jun 2017

Conference

Conference2017 IEEE 44th Photovoltaic Specialists Conference (PVSC)
CityWashington, D.C.
Period25/06/1730/06/17

Bibliographical note

See NREL/CP-5K00-74000 for paper as published in IEEE proceedings

NREL Publication Number

  • NREL/CP-5J00-68601

Keywords

  • adhesion
  • encapsulant
  • EVA
  • metallization
  • PV module reliability

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