This article discusses the lightning protection performance of a grounding grid for photovoltaic (PV) systems protected by independent lightning rods. Several grounding grid configurations are investigated, and the transferred voltages between the dc cables and supporting structures at different points in the PV system are evaluated using the finite difference time domain (FDTD) method. In the PV system without a dedicated grounding grid for supporting structures, the transferred voltage is very high, and is even worse if the soil resistivity is high. Installing a dedicated grounding grid, which is very costly in a large PV power plant, can reduce the amplitude of the transferred voltage and eliminate the residual voltage effectively. It is found that the arrangement using a bonding network is superior to other grounding improvement approaches in lightning protection. More importantly, the proposed approach is simple to implement and cost-effective. With the bonding network, the soil with high soil resistivity will not lead to severe overvoltage in the system. It is highly recommended to be adopted in the PV power plant protected by independent lightning rods.