Acceleration of potential-induced degradation by salt-mist preconditioning in crystalline silicon photovoltaic modules

We examined the sequential effects of salt-mist stress followed by high-system-voltage stress on the power loss of crystalline silicon photovoltaic (PV) modules to determine whether a crucial failure as potential-induced degradation (PID) is accelerated by material-property changes caused by the long-term effects of a less harmful stress such as salt-mist spraying. Degradation profiles confirmed in this study show that PID is accelerated by certain types of salt-mist preconditioning. For the acceleration of PID, the contribution of sodium ions liberated from the front glass of the PV module seems to be excluded. Therefore, we consider that the sodium ions penetrating into the PV modules from the ambient environment may also cause degradation according to the proposed mechanisms of PID, as the sodium ions existing in the front glass cause PID. Furthermore, this type of degradation may indicate the wear-out phenomenon after a long-term exposure in the field (especially near the coast). (C) 2015 The Japan Society of Applied Physics