4. 1 PV Module Design, Manufacture, Performance and Reliability
Degradation, Modelling / Modeling, Module
Summary / Abstract:
Due to the non-negligible electrical conductivity of module building materials, small leakage currents flow between the grounded module frame and the active cell matrix in photovoltaic (PV) modules under normal operation conditions, which can lead to significant degradation, such as e. g. potential-induced degradation of the shunting type (PID-s). In general, the degradation rate is strongly correlated with the leakage current density, which is highly dependent on the position in large-area modules due to the voltage drop between the frame and the cells. In this work, we present easy-to-use mathematical equations for rapid analytical calculation of the spatial leakage current density distribution in PV modules as a function of distance from the grounded module frame. The validity of the equations is confirmed by numerical simulation of a resistor network. As an applica- tion, the leakage current density distribution in a standard c-Si PV module was analytically calculated as a function of temperature and relative humidity, and the width of the circumferential module area threatened by PID-s was predicted under accelerated test conditions.