Investigating PV Generation Induced Voltage Volatility for Customers Sharing a Distribution Service Transformer

The number of grid-connected rooftop solar photovoltaic (PV) systems is expected to increase significantly in the next few years. Many studies have been conducted on analyzing transmission level voltage stability with high PV penetration, and recent efforts have also analyzed voltage stability at the medium- and low-voltage distribution levels. However, those studies have not considered detailed distribution secondary modeling extending from the primary feeder to the service transformer and all the way through the distribution secondary connections and service drops. This study investigates how variable rooftop solar PV generation impacts voltages at customers sharing a service transformer. Several different types of secondary system topologies are taken into account. A set of rules is presented that can be used to ascertain the level of voltage volatility expected as the solar PV generation varies.