Title :
Weathering degradation of EVA encapsulant and the effect of its yellowing on solar cell efficiency
Author :
Pern, FJ ; Czanderna, A.W. ; Emery, K.A. ; Dhere, R.G.
Author_Institution :
Nat. Renewable Energy Lab., Golden, CO, USA
Abstract :
After five or more years of weathering, the degradation of ethylene-vinyl acetate (EVA) encapsulant in photovoltaic (PV) modules resulted in a yellow to dark brown color. Degraded EVA shows a substantial increase in the gel content and a large to complete loss of the ultraviolet (UV) absorber, Cyasorb UV 531. The EVA discoloration is caused by the formation of polyconjugated (C=C)n double bonds of various lengths. Acetic acid and other volatile organic components are also produced from the photothermal decomposition of the EVA. The solar cell efficiency was reduced by ~9% by a light-yellow-brown EVA and ~50% by a dark-brown EVA. Weathered PV modules with dark-brown EVA also show a ~50% decrease in efficiency
Keywords :
polymers; solar cells; Cyasorb UV 531; EVA encapsulant; UV absorber loss; acetic acid; dark-brown EVA; ethylene-vinyl acetate; gel content; light-yellow-brown EVA; polyconjugated double bonds; solar cell efficiency; weathering degradation; yellowing; Glass; Laboratories; Photovoltaic cells; Photovoltaic systems; Quantum computing; Renewable energy resources; Solar energy; Stability; Thermal degradation; Wavelength measurement;
Conference_Titel :
Photovoltaic Specialists Conference, 1991., Conference Record of the Twenty Second IEEE
Conference_Location :
Las Vegas, NV
Print_ISBN :
0-87942-636-5
DOI :
10.1109/PVSC.1991.169275
