Fault diagnosis of photovoltaic modules using AC impedance spectroscopy

Availability of photovoltaic module fault diagnosis using AC impedance spectroscopy were investigated. Recently, there have been many reports about degradation and failure which occur to polycrystalline silicon photovoltaic modules. Because of these reasons, various diagnosis tools for photovoltaic modules have been invented and introduced; however, the fault mode is hard to determine. Thus, we have been proposing the application of AC impedance spectroscopy, which is widely used to evaluate electrochemical devices, as a diagnosis tool for photovoltaic modules. In this study, we conducted crack test and interconnect ribbon disconnection test to obtain and compare impedance characteristics and I-V characteristics. Equivalent circuit parameters calculated from Nyquist plots as impedance characteristics yielded information to differentiate the fault mode of photovoltaic modules; cracks on photovoltaic modules decrease the parallel resistance and increase the parallel capacitance; interconnect ribbon disconnection increases the series resistance and decreases the parallel resistance. We concluded that AC impedance spectroscopy can detect failures themselves and probably differentiate failure types of photovoltaic modules that cannot be distinguished using I-V characteristics.