PID issues in thin-film PV plants

摘要

Thin-film plants which were installed within the past 10 years have been known to suffer from quality issues such as underperformance and poor module quality. Potential-induced degradation could be identified as one of the major defect types, which sometimes results in an underperformance far beyond the warranty terms. Affected projects end up in legal confrontations and quite often require technical experts to evaluate the situation and to determine and validate the failure. Finally, in many cases the modules must be replaced. In recent years, results of PID-affected PV plants have been collected by the authors showing underperformance. Results of three investigated plants are presented in which the performance of the technologies CIGS, CdTe and μc-Si was studied. Investigation and characterization in the field and in the laboratory, including PID tests, were performed. The CdTe modules during field investigations show a clear degradation towards the negative string end. The PID test proved their sensitivity to the phenomenon and revealed TCO-corrosion. For μc-Si TF modules a PID sensitivity could also be proven but here the power evaluation and failure distinguishing to the "white spot" phenomenon was challenging. The CIGS modules under investigation showed also a very clear PID degradation towards the negative string end which could be proven by PID tests and electroluminescence on complete strings in the laboratory.