Is Damp Heat Degradation of c-Si Modules Essentially Universal?

Solar panel degradation has been the subject of careful research for many years in academic, national, and industrial laboratories. Unfortunately, the accelerated test data have been collected with different stress conditions and stress duration and interpreted and projected to the use condition by different reliability models, giving the appearance of reliability phenomena that are actually controlled by manufacturing variability, rather than intrinsic degradation parameters. In this paper, we demonstrate a simple and powerful new algorithm that can be used to interpret the existing (and widely scattered) experimental data within a common framework. The universal scaling shows that despite the manufacturing variability, the degradation modes in modern c-Si modules are essentially universal. The physical parameters extracted from the universal model provide deep insights into the degradation mode. More importantly, the approach will facilitate exchange/comparison/reuse of reliability information among various laboratories, help develop new characterization protocols, and allow accurate prediction of module lifetime.