On-line Electrochemical Impedance Spectroscopy method for PV diagnosis system

PV fault conditions in photovoltaic (PV) systems reduce panel power performance and accelerate cell degradation. In this way, many research have recently turned to the diagnosis of PV generator to minimize the cost of the produced energy and ensure reliable power production. This paper proposes a new PV diagnosis system based on on-line Electrochemical Impedance Spectroscopy. This latter is used to estimate internal parameters of PV panel connected to a resistive load via a DC/DC boost converter. The Nyquist Diagram allows to plot and evaluate dynamic impedance response versus variable low frequency signal injected in conjunction with the high frequency system allowing to operate the PV in MPPT condition. The dynamic single diode model with a series resistance, a shunt resistance and a junction capacitance is used to design the PV model in MATLAB/Simulink. Simulations results are given for normal and for faulty operation whether in the PV panel or in the load. Referring to these results, it is concluded that the proposed diagnosis method allows to detect PV panel faults regardless of load variation.