Photovoltaic Array Differential Backside Exposure Conditions: Backsheet Degradation and Site Design

Backsheet exposure conditions and degradation are shown to vary significantly within an array. This is demonstrated by a survey of the NIST ground-mounted photovoltaic array, which is comprised of over 1000 modules with a polyester-based backsheet. Site and array design factors are found to have significant effects on the exposure conditions, and thus degradation of the backsheets. Backside irradiance is found to be the most significant exposure factor which varies within the array.