Analytical evaluation of the ageing induced changes of the adhesive within photovoltaic backsheets

Abstract

The ageing stability of multilayer laminates - which are commercially used as PV backsheets - was examined in artificial weathering experiments. The impact of environmental factors like temperature, humidity and/or corrosive gases (ammonia) on the materials as well as on the ply adhesion within the multilayer laminate was investigated. The cross-sections of single backsheets and of backsheets integrated in PV-modules were investigated spectroscopically in the original and aged state in order to describe the impact of the environmental factors and lamination process on the adhesive layers. The spectroscopic information obtained on the evenness, thickness and chemical structure of the adhesive layer by Raman-imaging and infrared (IR)-imaging was in good accordance. Storage under damp heat conditions and humid ammonia atmosphere resulted in changes (chemical and physical degradation) of the adhesive. The magnitude of the effects, however, was strongly depending of the backsheet components and the influencing factors. Adhesive degradation was not always correlated with delamination behaviour.