Performance variation of dark current density-voltage characteristics for PID-affected monocrystalline silicon solar modules from the field

Potential-induced degradation (PID) has caught considerable attention in recent years because of its detrimental influence on output power of solar module and energy yield of photovoltaic power plant. In this paper, performance variation of dark current density-voltage (dark J-V) characteristics for PID-affected monocrystalline silicon solar modules dismounted from photovoltaic power plant was investigated. By measuring dark J-V characteristics of the PID-affected modules, the deterioration trend of dark J-V characteristics for PID-affected modules was found for the first time. Based on diffusion theory of metal ions, a new field-assisted diffusion model of metal ions was built, and the deterioration of open-circuit voltage and increase of recombination current density were explained for solar modules affected by PID. The thermal characteristics of solar modules with different level of PID were revealed under forward and reverse bias. There is an obvious temperature difference between the substrings neighboring the frame and the middle substring within the PID-affected modules. The results obtained in this paper give out the reasonable explanation about mechanism of PID and the deterioration trend of dark J-V for PID-affected modules.