Abstarct: This thesis presents a single-phase grid-connected photovoltaic (PV) system with reactive power control for residential applications. In order to design this system, these subjects have been considered: inverter and its switching method, controller system and reactive power control strategy. The inverter used in this system is HERIC (Highly Efficient and Reliable Inverter Concept) with unipolar switching method, which offers a better performance than the typical full-bridge structure. The PV controller system is designed to provide reactive power control with optimal system performance. Since this photovoltaic system can control reactive power, a strategy is proposed to control grid voltage during faults. Finally, the accuracy of the designed system performance is demonstrated by simulation in MATLAB Simulixnk. The simulation results show that the designed photovoltaic system, along with the reactive power control strategy, can provide grid voltage compensation during faults, in addition to injecting the active power to the grid.