Comparative Study on Reverse Current for PID-Affected and PID-Free Crystalline Silicon Solar Module

In this paper, a comparative study on the reverse current of crystalline silicon solar module was carried out based on the PID recovery experiments. First, the thermography and electroluminescence images of PID-affected and PID-free solar modules were investigated. It is found that there is a good agreement between the electroluminescence images and the thermographic images for PID-affected and PID-free solar module. And then, a PID recovery experiment was performed in our laboratory. It is found that, for the PID-affected solar module, the PID caused power degradation could be gradually recovered with the increasing recovery time. By contrast, for the PID-free solar module, there is almost no change of reverse current for solar module during recovery. Moreover, an important finding is that, for the PID-affected module, the reverse current of solar module decreases with the increasing of recovery time. Especially, it decreases drastically at the early recovery stage (< 60 h). However, this conclusion does not hold true for the PID-free solar module. The obtained results could provide an accurate PID detection method.