Photovoltaic manufacturing technology (PVMaT). Semiannual subcontract report, March 31, 1994--September 30, 1994

Technical Report · Sat Apr 01 04:00:00 EST 1995

DOI:https://doi.org/10.2172/64201· OSTI ID:64201

Holley, W

The following highlights key findings from this reporting period: while {open_quotes}standard cure{close_quotes} A9918P ethylene vinyl acetate (EVA) encapsulant, laminated between low iron glass, shows significant yellowing after 17 weeks in a xenon-arc Weather-Ometer, {open_quotes}neat{close_quotes} EVA with no additives shows little or no yellowing after the same exposure; when similar laminates were prepared and exposed in the Weather-Ometer, using A9918P with the Lupersol 101 crosslinker removed from the encapsulant, color development after 10 weeks was reduced by approximately 2/3. This result strongly implicates Lupersol 101 in the discoloration of EVA encapsulant; similar Weather-Ometer aging studies of other laminates, prepared using EVA with various combinations of the A9918P additives, suggests that EVA discoloration arises primarily from Naugard P and an interaction of Lupersol 101 with Cyasorb UV-531. Transformation products of these additives appear to be giving rise to yellowing, rather than the Elvax 3185 resin itself; when Lupersol TBEC was substituted for Lupersol 101 in the encapsulant (i.e. {open_quotes}fast cure{close_quotes} 15295P formulation rather than the {open_quotes}standard cure{close_quotes} A9918P), the rate of yellowing was reduced by a factor of approximately 2.5; use of a cerium-oxide containing low-iron glass superstrate reduced the rate of yellowing of A9918P EVA by approximately 75%. When laminates were prepared and exposed using 15295P EVA and cerium-oxide containing glass superstrate, there was no visible yellowing. Analytical results show no measurable loss of acetic acid from very browned, field-aged EVA and no evidence of conjugated unsaturation; analysis also reveals the loss of Cyasorb UV-531 in both field-aged and laboratory U.V. aged samples, but only in the presence of Lupersol 101. This result supports the finding of an interaction of Lupersol 101 with UV-531 as contributing to color formation in the presence of U.V.

• Research Organization: National Renewable Energy Lab., Golden, CO (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC36-83CH10093
• OSTI ID: 64201
• Report Number(s): NREL/TP--411-7693; ON: DE95004093
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ADDITIVES
COLOR
COPOLYMERS
ENCAPSULANTS
ENCAPSULATION
ETHYLENE VINYL ACETATE
GLASS
MANUFACTURING
NONDESTRUCTIVE TESTING
OXIDATION
PEROXIDES
PHOTOVOLTAICS
POTTING MATERIALS
PROGRESS REPORT
SOLAR CELLS
ULTRAVIOLET RADIATION
WEATHERING