Uncertainities and variations of power generation through photovoltaic (PV) sources are major challenges for theirintegration with the distribution grid. Voltage rise and voltage drop issues limit the increase in PV penetration and loading levels,respectively. Moreover, it is important to maintain voltage levels as per grid code while ensuring that the PV power generation isnot curtailed. In this paper, a voltage control method using smart transformer (ST) via dynamic optimal setpoints and limittolerance is proposed in a residential distribution network. Performance indicators are developed to understand the impact ofthe proposed method on the system voltage profile. A method to determine the optimal inputs for voltage control methodsdepending on the day-ahead predictions of load demand and PV power profiles is developed. Further, a voltage control methodof switching among three setpoints based on the voltage that determines the load side ac reference voltages for ST is proposed.The proposed method is compared with the method of switching between two setpoints based on current. The proposed methodprovides an improved voltage profile in the distribution network, which is tested on a CIGRE low voltage residential distributionnetwork using PSCAD.