Voltage-rise problems caused by residential photovoltaic (PV) systems in low-voltage distribution networks represent significant technical constraints in smart grid environments. This paper analyzes the influence of a PV system's installation location on voltage-rise phenomena in single-phase, three-wire low-voltage distribution networks. In particular, every customer has a different impact on the voltage-rise effect, depending on the length of the service wires; the impedance (particularly the resistance component) of service wires is higher than that of other wires in higher-voltage networks. In order to minimize the restriction of PV output, this paper evaluates the optimal restriction dispatch of PV output among customers with PV. Moreover, assuming the future availability of energy management systems, it aims to prevent voltage constraints by improving the imbalances of 100 V loads in single-phase three wire distribution networks.