Assessment of PV module durability using accelerated and outdoor performance analysis and comparisons

Photovoltaic modules have been operating in the outdoor environment for more than 30 years now. These modules have been exposed to a wide range of stresses including UV and visible radiation, high and low temperatures, seasonal and diurnal temperature variations, internal electric field, localized heat, moisture including rain, humidity and condensation, abrasion and other mechanical stresses. Over these 30 years, qualification requirements have been imposed to identify infant mortality failures in module design and materials, but much work remains in understanding the durability issues related to module performance and safety. In this paper, we will review analysis of modules taken from the field and discuss changes in the module performance as they relate to materials performance and changes. We will also discuss our work in simulating these stresses in accelerated durability testing and compare changes in module performance and safety to those observed in the field. Finally, we will review progress in simulating outdoor conditions using combinations of stresses applied to the module to better simulate outdoor conditions.