Artificial Linear Brush Abrasion of Coatings for Photovoltaic Module First Surfaces

Jimmy Newkirk, Illya Nayshevsky, Archana Sinha, Adam Law, QianFeng Xu, Bobby To, Paul Ndione, Laura Schelhas, John Walls, Alan Lyons, David Miller

Research output: NRELPresentation


Natural soiling and the subsequent requisite cleaning of photovoltaic (PV) modules result in abrasion damage to the cover glass. The durability of the front glass has important economic consequences, including determining the use of anti-reflective and/or anti-soiling coatings as well as the method and frequency of operational maintenance (cleaning). Artificial linear brush abrasion using Nylon 6/12 bristles was therefore examined to explore the durability of representative PV first-surfaces, i.e., the surface of a module incident to direct solar radiation. Specimens examined include silane surface functionalized-, roughened (etched)-, porous silica-coated-, fluoropolymer-coated-, and ceramic (TiO2 or ZrO2/SiO2/ZrO2/SiO2)-coated-glass, which are compared to monolithic-poly(methyl methacrylate) and -glass coupons. Characterization methods used in this study include: optical microscopy, ultraviolet-visible-near-infrared (UV-VIS-NIR) spectroscopy, sessile drop goniometry, white-light interferometry, atomic force microscopy (AFM), and depth-profiling X-ray photoelectron spectroscopy (XPS). The corresponding characteristics examined include: surface morphology, transmittance (i.e., optical performance), surface energy (water contact angle), surface roughness, scratch width and depth, and chemical composition, respectively. The study here was performed to determine coating failure modes; identify characterization methods that can detect nascent failures; compare the durability of popular contemporary coating materials; identify their corresponding damage characteristics; and compare slurry and dry-dust abrasion. This study will also aid in developing an abrasion standard for the PV industry.
Original languageAmerican English
Number of pages41
StatePublished - 2019

Publication series

NamePresented at the 2019 International PV Soiling Workshop, 28-30 October 2019, Marrakech, Morocco

NREL Publication Number

  • NREL/PR-5K00-75028


  • abrasion
  • anti-reflective coating
  • anti-soiling coating
  • erosion
  • operations maintenance


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