Characterizing bulk and interface behavior of encapsulants within photovoltaic laminates

Abstract

Climate-induced degradation modes will affect the efficiency and lifetime of the photovoltaic (PV) modules. Among the most common degradation modes, the most prevalent one is the failure of the interconnection, followed by delamination. Delamination can occur between different components in the PV-laminate. However, in the case of encapsulant-cell delamination, it seems to happen selectively around the screen-printed contacts. The objective of this master thesis is to study delamination by characterizing the parameters which contribute to the adhesion between the interconnection and the encapsulant. The roughness of a surface is a key parameter that has a significant influence on the adhesion strength. It has also been shown that the effect of roughness is influenced by the mechanical behavior of the adhesive. Therefore, these two parameters are studied to characterize the adhesion. Primarily, the adherend surface is characterized completely with a confocal laser scanning microscope. Subsequently, the mechanical properties of the encapsulant are determined by using the technic of dynamic mechanical analysis. A material model is fit to the experimental results to use this as an input for reliability models. Finally, the influence of process parameters, various encapsulants as well as the different metal contacts are examined with a scanning electron microscope.