Effects of equipotential bonding strategies on the transient step voltage in ground-mounted PV power plants

In order to guarantee the availability of PV (photovoltaic) power plants and ensure personal safety, lightning protection measures are implemented. The installation of a lightning protection system, incorporating earthing systems and equipotential bonding, has been shown to increase investment costs. Consequently, the effectiveness of various strategies employed in such systems requires further investigation. However, the transient calculations required for large power plants are complex. In this research paper, a case study of various large-scale ground-mounted PV installations is described, and the transient surface potential is calculated to determine the transient step voltage. The effectiveness and necessity of earthing bonding strategies are verified to ensure personal safety in the event of lightning-induced currents. The personal safety limits are specified in the IEC 62305 series of standards. Although the impedance to earth for driven steel rods that function as the foundation of substantial PV installations is low at power frequency, the specified limit for step voltage cannot be met without employing a suitable earthing bonding strategy. This is particularly the case when considering the necessity for different distances between the bonding wires, which depend on the soil resistivity.