The effect of metal foil tape degradation on the long-term reliability of PV modules

A program is underway at Sandia National Laboratories 1 to predict long-term reliability of photovoltaic systems. The vehicle for the reliability predictions is a Reliability Block Diagram (RBD), which models system behavior. Because this model is based mainly on field failure and repair times, it cannot currently be used to accurately predict end-of-life. In order to be truly predictive, physics-informed degradation processes and failure mechanisms need to be included in the model. This paper describes accelerated life testing of metal foil tapes used in thin-film PV modules, and how tape joint degradation, a possible failure mode, can be incorporated into the model.