This research considers some smart inverter functions of photovoltaic (PV) generations as options for power utilities to improve system performance. The potential impacts of these functions on voltage, energy loss, and power curtailment are investigated first. Then, parameters of volt-var and volt-watt control are coordinated with a step voltage regulator to minimize the social cost. After that, simulations of a tested system containing a 6.6kV-feeder, which includes large-scale PVs, and low-voltage networks, which contain a large number of rooftop solar panels, are performed in the OPENDSS software with real data collected in Japan. Results show that appropriate smart inverter functions can be remedies for an overvoltage issue caused by high PV generation. Although the energy loss may be higher than that of the no-control case, parameters of smart functions and utility devices could be set optimally to balance the capital conflicts between utilities and PV owners on a daily basis.