Spatially Resolved Degradation Analysis of Solar Modules After Combined Accelerated Aging

The degradation behavior of solar modules was investigated under combined damp heat and UV weathering conditions. A full electrical characterization, including electro luminescence measurements, shows a severe module degradation after 2000h, with power losses exceeding 60%. A chemical analysis of the encapsulation material on the basis of ethylene-vinyl acetate copolymer, extracted directly from the weathered modules, reveals a clear dependence of the encapsulant degradation on the position in the module and the weathering time. Remarkably, the consumption of the UV stabilizer in the encapsulant correlates to the degradation of the encapsulation material and finally to the degradation of the solar module. This finding emphasizes the relevance of the quality control of the encapsulant formulation for the module reliability.