Solarex experience with ethylene vinyl acetate encapsulation

Solarex began using ethylene vinyl acetate (EVA) as an encapsulant for photovoltaic modules during the Jet Propulsion Laboratory sponsored Block IV Program in 1979. Experience was gained in the processing and use of EVA during a number of Department of Energy sponsored projects through the early 1980s. In 1982 Solarex began using EVA in commercial modules and has continued to use it up to the present time. EVA has proven to be a highly reliable encapsulant, with no reported instances of Solarex module field failures being attributed to failure of the EVA encapsulant. The EVA encapsulation system is complex, requiring well controlled manufacture of the film itself and the correct lamination procedure to assure adequate cure and bonding to the glass, cell and backsheet surfaces. The initial Springborn work on EVA included accelerated testing, which indicated that at temperatures considerably higher than experienced during normal module operation, the EVA system will suffer thermally induced degradation. However, no major degradation was experienced under normal operating conditions during either Springborn's testing or Solarex's 10 years of field experience.