The penetration of photovoltaic (PV) systems has recently been increased in distribution systems. Many practical problems are resulted by the fluctuating PV systems, including voltage rise/drop and increasing the total active/reactive losses. In this paper, we propose a method for solving the practical problems associated with PV by optimally increasing the capacity of the PV inverter over the capacity of the PV modules. An optimization model is constructed to calculate the optimal inverter capacity while minimizing the cost of the inverter, the cost of the curtailed power, the cost of losses in the distribution system. The overall system constraints are considering in the optimization model. The proposed method is tested using the IEEE 69-bus distribution system. The effectiveness of the proposed method is demonstrated by calculating the optimal capacity of the PV inverter for mitigating the technical impacts of PV.