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REVISED DRAFT 2015-7-7 Soiling of building envelope surfaces-Part III

Mirror augmented photovoltaic (MAPV) systems utilize low cost mirrors to couple more light into a photovoltaic (PV) absorber. By increasing the light absorbed, they are expected to produce less expensive electricity. As a substrate candidate for back surface reflector mirrors, two grades of PMMA have been exposed to UV stress from two sources at two intensities for two doses in an effort to see the response of materials under different states of stress and after exposure to different amounts of total stress. By developing a framework for correlating stresses, such as short wave ultraviolet radiation, with responses, such as induced absorbance and yellowing, mirror durability we have made progress in developing lifetime and degradation science using mirror durability as a case study. All of the samples showed similarities in their degradation characteristics. The UV stress acceleration factor was quantized as 10.2 in short wave ultraviolet irradiance, and 15.8 in total shortwave UV dose. The effects of UV absorbers in protecting the polymer from degradation are discussed. Further study into degradation mechanisms will elucidate the exact phenomena that contribute to these material responses to stress.