Photovoltaic Manufacturing Technology (PVMaT): Semiannual Subcontract Report, 31 March 1994 - 30 September 1994

This report describes work performed under the Photovoltaic Manufacturing Technology (PVMaT) Project. Major accomplishments reported in this document include the following: (1) While 'standard cure' A9918P ethylene vinyl acetate (EVA) encapsulant, laminated between low-iron glass, showed significant yellowing after 17 weeks in a xenon-arc Weather-Ometer, 'neat' EVA with no additives showed littleor no yellowing after the same exposure. (2) Similar laminates, prepared and exposed in the Weather-Ometer using A9918P (standard cure EVA) with the Luperson 101 removed from the encapsulant, showed approximately a 2/3 reduction in color development after 10 weeks. (3) Studies suggest that EVA with various combinations of the A9918P additives shows discoloration primarily from Naugard P and aninteraction of Lupersol 101 with Cyasorb UV-531. (4) Luperson TBEC (an organic peroxide) reduced the yellowing rate by a factor of approximately 2.5 based on 17 weeks exposure. (5) A cerium-oxide, containing a low-iron glass superstrate, reduced the rate of yellowing of A9918P EVA by approximately 75% after 17 weeks exposure. (6) Laminates, prepared and exposed using 15295P (fast cure EVA) andcerium-oxide containing glass superstrate, showed no visible yellowing after 17 weeks. (7) Preliminary analytical results showed no measurable loss of acetice acid from very browned, field-aged EVA and no evidence of conjugated unsaturation. (8) Analysis also revealed the loss of Cyasorb UV-531 in both field-aged and laboratory ultraviolet (UV)-aged samples, but only in the presence of Lupersol101.