PV Installation Design Influencing the Risk of Induced Currents from Nearby Lightning Strikes

Bypass diode failures were observed within three utility-scale photovoltaic (PV) plants after thunderstorm activity, with no evidence of direct lightning strikes to the PV plant. This paper investigates the mechanisms by which currents may be induced within PV installations. Firstly, computational electromagnetic simulations are performed for both a standalone PV model, as well as a series-connected array of four PV modules. Secondly, real-world testing with an actual PV module, as well as a thin-wire model of a PV module, was performed in a high-voltage laboratory. These investigations were conducted with the objective of minimizing the magnitudes of induced currents within a PV installation. It was found that poor inter-module wiring in a PV installation, and not the internal layout of the PV modules themselves, resulted in the largest magnitudes of the induced currents, and that better wiring practice would significantly reduce these magnitudes. The presence and geometry of the conductive frame of a PV module was shown to reduce the magnitude of the currents induced within the installation.