Due to distinct characteristics between the synchronous generators(SGs) and PV systems, it is challenging and sometimes erroneous to directly apply today’s earthing schemes to the PV system since they are mainly designed for SGs. Improper earthing can cause neutral point shifting under asymmetrical faults and thus serious overvoltage problems. In order to address such issues, voltage characteristics of synchronous generators and inverter based distributed energy resource during a single-line-to-ground fault are theoretically calculated and compared in this paper. Simulation results from an example PV system model in Matlab/Simulink verify the overvoltage characteristics provided by the different earthing configuration, such as the proportion of grounded load, the installation of grounding transformer and surge arrester.