Search

The aim of these investigations was to develop, implement and evaluate an appropriate procedure in order to qualify new polymeric components for the use in PV modules and to predict the lifetime of materials and modules. A test program concerning five accelerated artificial aging tests (varying UV, temperature and humidity levels) was set up and the degradation behavior of six polymers was investigated. Visual transmittance and strain-at-break were identified as most significant degradation indicators. A suitable material specific material degradation model was obtained, where changes of the material properties are accurately related to the applied environmental stresses. For the modeling of service life time the micro-climate, to which the encapsulation materials are exposed in a PV-module, was considered and reasonable end-of-life criteria were defined. Accelerated aging tests showed that effects of heat and humidity are dominating in optical properties, whereas changes in mechanical properties are equally effected by UV and humidity. An exact description of the micro-climate was found to be most critical for the accuracy of the material degradation model. For first qualification of the principal applicability of new materials both, a standard damp heat test and a UV test have to be done in order to validate all degradation effects properly.