A straightforward method to extract the shunt resistance of photovoltaic cells from current–voltage characteristics of mounted arrays

A straightforward non-invasive method is proposed to accurately evaluate the shunt resistance of an elementary cell of a photovoltaic module connected in an installed string without requiring prior knowledge of the parameters of the intrinsic diodes. The approach relies on the measurement of the current–voltage characteristic of the whole string after intentionally shading the selected cell. Calibrated PSPICE simulations are employed to illustrate the method and test its reliability. As a case study, the shunt resistances of several cells belonging to a series array of 10 commercial panels are determined.

► We extract the shunt resistance of selected cells in installed photovoltaic arrays.
► Despite its simplicity, the approach guarantees a high level of accuracy.
► The shunt resistance can be determined without knowing the intrinsic diode features.
► Panels belonging to the same family are found to show different levels of quality.