Lightning-Induced Voltages Risk for Microinverters in Photovoltaic Installations

The effects of lightning on electrical systems have been a topic studied extensively in the past several years. Despite this establishment, the induced and indirect effects of lightning on microinverters used in Photovoltaic Installations (PVIs) have not been studied in detail. This includes voltage induced in the power cables of the solar cell arrays in the event of partial lightning currents. The lack of such information is a barrier to determining the voltage, current and energy characteristics when developing surge protection devices (SPDs) to protect photovoltaic (PV) systems with microinverter technology. This study was performed through experimental work, where impulse current was injected on the lightning rod and the frame of the PV system. The resulting induced voltages were measured in Differential Mode (DM) and Common Mode (CM) configurations with and without the microinverter connected. It was found that lightning currents flowing through Lightning Protection System (LPS) structures or the PV frame can cause transient overvoltages on the DC cabling of a PVI. The magnitudes of these overvoltages varied as a function of several parameters, including, the lightning current amplitude, protection scenario, and mode of measurement.