Fault detection in a photovoltaic plant by time domain reflectometry

A reflectometric technique has been developed for diagnostic monitoring of a photovoltaic plant. Detailed information on the position and type of fault is inferred from the shape of the voltage waveforms resulting when a pulsed voltage excitation is applied to a string consisting of several series-connected modules. When an open circuit or a short circuit to ground are occurring, direct reading of the results is obtained by means of a software tool performing numerical analysis of the digitized waveforms. Extensions of this approach to the case of parallel-connected strings, as well as to the cases of a loaded plant and no illumination, are discussed.