A high density of grid-connected photovoltaic (PV) power generation systems is expected to occur in urban areas. The connection of distributed generation (DG) may cause serious problems in the distribution system such as voltage rise. Several voltage control strategies exist to avoid the over-voltage at the power grid. In particular, reactive power control methods have been proved to successfully bring DGs voltages within the admissible voltage range without reducing the production of active power. In addition, the possible use of communication infrastructure to link DGs opens up the development of new reactive power control methods where control actions at each DG may be decided using both local and global information. This paper presents a comparative study of existing and novel distributed reactive power control methods that have been designed exploiting the information exchange facility provided by a communication infrastructure.