AC Impedance Characteristics and Modeling of Electrical Leakage Circuit Within a Photovoltaic Module Installed in a Field

The electrical insulation resistance of photovoltaic (PV) modules plays an important role in maintaining the operational integrity of PV systems deployed in fields. This is because the breakdown of the electrical insulation of PV modules directly contributes to performance loss and electrical safety risks. To gain insight into the characteristics of the electrical leakage circuit between the PV cells and the metal frame of the PV modules as a substantial reflection of the behavior of the electrical insulation resistance in the PV modules, an analysis technique using ac impedance spectroscopy was applied to PV modules installed in a field. We identify the existence of an ionic diffusion element (Warburg impedance) in the circuit in addition to the elements consisting of the conventional parallel resistor–capacitor model including a series resistor. Thus, an ac equivalent circuit model, including these elements, was established for the electrical leakage circuit of the PV module. Given the distinct dependencies of these elements on weather conditions, we propose a direct coupling of the resistive elements to the surface condition of the PV module. However, the Warburg impedance and capacitance are also linked to the conditions of the internal components within the PV module. Furthermore, by verifying the interrelationships among the ac impedance parameters in the ac equivalent circuit model, we can predict these values accurately in both dry and wet weather conditions. These findings would offer valuable perspectives for addressing concerns related to the decreased performance and potential safety risks of PV modules installed in various environments.