Solar energy has attracted considerable attention around the world. Commonly, the photovoltaic systems connected to the grid. PV systems can principally be integrated to the electrical grid via galvanic isolation (transformer) or without it (transformerless). Although the low frequency transformer makes galvanic isolation, it increases size, cost and losses. On the other hand, transformerless PV systems increase the leakage current (common mode current, (CMC)) through the parasitic capacitors of the PV array. The leakage current depends on several parameters, mostly inverter topology and switching technique. Since there is no need to additional hardware for switching scheme modification, it's an inexpensive method to reduce leakage current. This paper investigates the impact of various space vector modulation techniques on leakage current for a two-level three-phase four-leg inverter used in PV system, as a new study. It proposes an effective space vector modulation technique which reduces the leakage current to below the quantity specified in VDE-0126-1-1 standard. Moreover, some other characteristics of the space vector modulation schemes that have not been significantly discussed for four-leg inverter, are taken into account, such as switching actions per period, modulation index, common mode voltage (CMV), and total harmonic distortion (THD). An extend software simulation using MATLAB/Simulink is performed to verify the effectiveness of the proposed modulation technique.