Transformer-less photovoltaic (PV) inverters are the major functional units of modern grid-connected PV energy production systems. In general, two power conversion stages are required when low-voltage unregulated photovoltaic (PV) output is conditioned to generate AC power. In this paper, the boost inverter topology that achieves both boosting and inversion functions in a single stage is used as a building block to develop a three phase grid connected PV system which offers high conversion efficiency, low-cost and compactness. The proposed system employs a modified modulation scheme for the three phase boost inverter to control both active and reactive power injected to the grid. This modified modulation scheme enhances the boosting capability of the boost inverter and improves the THD of the grid injected current. Moreover, it reduces the voltage stress on the capacitors and switching devices. Analysis and simulation results are presented to confirm the advantages and efficiency of the proposed modulation technique.