BACKFLIP: A Comparison of Emerging Non-Fluoropolymer-Based, Co-Extruded PV Backsheets to Industry-Benchmark Technologies

Michael Thuis, Naila Al Hasan, Rachael Arnold, Bruce King, Ashley Maes, David Miller, Jimmy Newkirk, Laura Schelhas, Archana Sinha, Kent Terwilliger, Sona Ulicna, Kurt Van Durme

Research output: NRELPresentation


As the photovoltaic (PV) industry is rapidly expanding around the world, there has been an increasing interest in extending the lifespan of PV modules. Concern has also emerged regarding the recyclability of modules and their component materials, including fluoropolymer-based backsheets. Laminated polyethylene-terephthalate (PET) core backsheets have traditionally been used in the PV industry, but new, co-extruded polyolefin (PO) backsheets show promise as an improved alternative. Mini-module and coupon samples of seven different backsheets (made of layers including contemporary PET and fluoropolymers, novel PO, and polyamide (PA) materials) were run through hygrometric- or UV photolytic-accelerated aging to identify and better understand each material’s degradation modes and the backsheets’ field reliability. In addition to the artificial aging, the natural weathering methods used in this study are described. The comprehensive set of chemical, mechanical, and structural characterizations at intermittent read points in this study is presented, including: visual appearance and color; gloss; mechanical tensile testing; I-V performance; electroluminescence (EL) imaging; dielectric breakdown; FTIR-chemical structure; X-ray-polymer structure (WAXS); and DSC-crystalline content. After 4000 h of aging, a strong correlation occurs between initial physical characteristics (mechanical tensile test) and operating performance (EL and I-V characteristics).
Original languageAmerican English
Number of pages20
StatePublished - 2021

Publication series

NamePresented at the 48th IEEE Photovoltaic Specialists Conference (PVSC 48), 20-25 June 2020

NREL Publication Number

  • NREL/PR-5K00-80362


  • backsheet
  • damp heat testing
  • durability
  • DuraMAT
  • IEC TS 62788-7-2
  • PET
  • polyolefin
  • UV weathering


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