Effects of outdoor exposure on solar cell modules in the ERDA/NASA Lewis Research Center Ststems Test Facility

Solar cell modules were removed from the ERDA/NASA Lewis Research Center Systems Test Facility and I-V curves obtained in the Lewis pulsed xenon simulator under standard conditions (air mass 1 and 28/sup 0/C). Modules involved were supplied by three vendors under the ERDA/JPL Low Cost Silicon Solar Array Project. Outdoor exposure times varied from 41 to 245 days. The effects of outdoor exposure were determined by comparing standard I-V data obtained for the as-received modules with similar data obtained after removal from the field and cleaning with detergent solution. All modules measured in this way exhibited nonrecoverable degradation in P/sub max/ varying from 4 to 7% and I/sub sc/ varying from 2/sup 1///sub 2/ to 5/sup 1///sub 2/%. One module exposed for 41 days exhibited partial cell discoloration, loss of front surface metallization over the discolored portion, and a decrease in P/sub max/ of 7%, tentatively attributed to cell damage. Measurements before and after cleaning showed a recoverable degradation due to dirt accumulation. This recoverable loss in power was 11% after 245 days in the field for one brand of module, 6% after 48 days for another brand, and 4/sup 1///sub 2/% for the third brand.