One of the main concerns of utilities is overvoltage along their feeders when they enhance their networks by various distributed generation (DG) systems. The objective of this study is (1) to near-optimally allocate locations and capacities of DG systems on distribution networks at peak load and (2) to analyze the impact of DG inverters with the capability of volt/var control on the improvement of the voltage profile along the feeder during steady state. This study proposes a genetic algorithm with an objective function that minimizes voltage variations caused by the installation of DG systems, near-optimally allocates the locations and the capacities of DG systems either with or without the capability of volt/var control on a distribution network at peak load, and analyzes their impact on the improvement of the voltage profile along the feeder.