Analysis of degradation in 25-year-old field-aged crystalline silicon solar cells

Abstract Photovoltaic (PV) modules have been in use for more than 25 years. The gradual degradation of PV modules is determined by its components and the solar cells. We analyzed the long-term reliability of solar cells using a 25-year-old field-aged PV module. The power of a large size PV module was reduced by approximately 24.6% owing to the delamination of two specific solar cell portions. For a single cell module from a large size PV module, the decrease of short circuit current (Isc) was caused by the discoloration of the ethylene-vinyl acetate. The maximum power (Pmax) decreased by 11.5% compared with its initial value; however, this is not an effect of the degradation of the solar cell. Despite being manufactured in the 1980s, these solar cells did not fail and have little power loss and excellent durability after 25 years.