An End of Service Life Assessment of PMMA Lenses from Veteran Concentrator Photovoltaic Systems: NREL (National Renewable Energy Laboratory)

David Miller, David Johnson, Todd Vinzant, Bobby To, Sarah Kurtz, Hussameldin Khonkar, Rebeca Herrero, Ignacio Anton, Thorsten Hornung, Tobias Schmid-Schirling, Gabriel Sala

Research output: NRELPresentation


The optical performance of poly(methyl methacrylate) lenses from veteran concentrator photovoltaic modules was examined after the end of their service life. Lenses from the Martin-Marietta and Intersol module designs were examined from the 'Solar Village' site near Riyadh, Saudi Arabia, as well as the Phoenix Sky Harbor airport, followed by the Arizona Public Service Solar Test and Research (APS-STaR) center in Tempe, Arizona. The various lens specimens were deployed for 20, 27, and 22 years, respectively. Optical characterizations included lens efficiency (Solar Simulator instrument), material transmittance and haze (of coupons cut from veteran lenses, then measured again after their faceted back surface was polished, and then measured again after the incident front surface was polished), and direct transmittance (as a function of detector's acceptance angle, using the Very Low Angular Beam Spread ('VLABS') instrument). Lens efficiency measurements compared the central region to the entire lens, also using hot and cold mirror measurements to diagnose differences in performance. A series of subsequent characterizations was performed because a decrease in performance of greater than 10% was observed for some of the veteran lenses. Surface roughness was examined using atomic force microscopy and scanning electron microscopy. Facet geometry (tip and valley radius) was quantified on cross-sectioned specimens. Molecular weight was compared between the incident and faceted surfaces of the lenses.
Original languageAmerican English
Number of pages57
StatePublished - 2015

Publication series

NamePresented at the 11th International Conference on Concentrator Photovoltaic Systems (CPV11), 13-15 April 2015, Aix-les-Baines, France

NREL Publication Number

  • NREL/PR-5J00-67733


  • AFM
  • CPV durability
  • Fresnel lens
  • photovoltaics
  • PMMA
  • reliability
  • SEM
  • solar


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