EMC issues in high-power grid-connected photovoltaic plants: an update after 15 years

This article revises and updates the electromagnetic compatibility (EMC) challenges commonly encountered in utility-scale grid-connected photovoltaic (PV) systems in light of modern trends. This article examines the issues related to the conductive and radiated radio-frequency disturbances, in the range from 150 kHz to 1 GHz, of multi-MWp PV plants as designed nowadays, with high-power bifacial modules, single-axis trackers, and decentralized high-density inverters. The main features include the extensive dc and ac cabling, the capacitance toward the Earth of the PV source, the common-mode disturbance caused by inverters, the effect of safety and functional grounding, the galvanic isolation provided by step-up power transformers, and the presence of resonant circuits for common-mode leakage currents. Measurements in situ for both conducted and radiated disturbances in a 19.87 MWp plant placed in Ferrandina, South Italy, are presented and discussed. Guidelines for achieving an EMC functional safety by design are provided, raising from the analysis of the measured data.