Defects and performance of Si PV modules in the field – an analysis

Abstract

Photovoltaic installations will likely become one of the major power sources in the 21st century and we need photovoltaic modules to operate reliably. In this review, we explore what is known today about the status of installed crystalline silicon photovoltaic modules in the world, how different sources classify module defects, and what we might deduce for future installations. Looking at more than 200 results from 132 installations and 79 reports, we find that PV modules in general are robust in outdoor operation, with about one in 250 modules failing completely each year. About one in ten modules will develop a defect resulting in greater than expected power loss throughout their lifetime, and practically every module will develop visually perceivable alterations. We observe no trends of changes over time in these findings, hence there is no indication that future performance will deviate dramatically. We note though that more information is needed. Available studies represent a module fleet with greater age than current installations, and are over-representing multicrystalline – compared to monocrystalline silicon, and AL-BSF – compared to PERC cell architectures. Studies from Asia and Africa and from tropical climates are underrepresented. A major challenge in the analysis was the variety of metrics used. To facilitate easier comparison, we propose reporting guidelines.