Partial shading detection on PV panels through on-line Impedance Spectroscopy

In this paper the effect of mismatch on the impedance spectrum of PV panel is investigated. The Electrochemical Impedance Spectroscopy (EIS) technique is applied to analyse the PV panel dynamic response through a detailed LTSpice model including by-pass diodes. Simulation results show that it is possible to detect partial shading conditions only by performing the EIS with the panel operating in MPP thus without scan the whole I-V curve. This confirms the usefulness of EIS applied to the PV panel not only for diagnosis purposes but also for supporting the MPPT algorithms to reach the global maximum in presence of mismatch.