Photothermal stability of encapsulated silicon solar cells andencapsulation materials upon accelerated exposures. II

摘要

The authors studied the electrical and optical performancestability of crystalline silicon solar cells that were encapsulated withdifferent types of EVA (ethylene vinyl acetate) between a borosilicateglass superstrate and a glass or white TPT (Tedlar/polyester/Tedlar)substrate. Total internal light reflection from the white TPT layerenhanced the measured cell photocurrent by ~20.4% to 23.9% and theefficiency by ~17.4% to 20.8%, with a cell-to-sample area ratio of23,3%. In comparison, the enhancements on the cell photocurrent werefrom ~5.0% to 7.0% when the cells were laminated between twoborosilicate plates. The samples were exposed under to ~6.5 UV suns at65° C or heated in an oven at 105° C and periodicallycharacterized for electrical and optical losses. The results show that,when the samples were measured without black-masking over the non-cellareas, the cell efficiency decreased by ~0.3% to 8.9% and the fillfactor changed by ~0% to 6.6% after 1133-h exposures. When the non-cellareas were masked, the measured cell efficiency losses became 4.1% to9.0% and the fill factor losses from 0.5% to 5.2%, respectively. Theelectrical changes are irregular for the sample cells tested and are notproportional to the optical losses of EVA/TPT bi-layer. As an example, acell's efficiency decreased by 8.9%, whereas is NREL-V11 EVA remainedclear; and another cell lost 7.1% efficiency, whereas its slow-cureA9918 EVA browned with a 12.2% loss in integrated transmittance and anincrease of 31.85 in yellowness index