Lightning-induced overvoltage protection for microinverters using surge protective devices

The need for a good quality power supply in PV systems makes lightning protection one of the primary requirements in Photovoltaic installations (PVIs). Surge Protective Devices (SPDs) are connected to the DC and AC cables in PVIs to protect the electronic components against lightning transients. In this paper, the protection of the microinverter against lightning transients was investigated by simulation using Power System Computer-Aided Design (PSCAD) software. A Metal Oxide Varistor (MOV) surge protective device was connected to the DC cables of a PV panel with a microinverter while subjected to lightning-induced overvoltage (LIO) stresses for various lightning current waveforms, amplitudes, and protection scenarios. This investigation measured the energy overload and the current flowing through the SPD. The results demonstrated that a class II internal SPD seems appropriate for PV installations with a microinverter with and without an external lightning protection system (LPS) for impulse currents not exceeding 20 kA.