Penetration of solar energy is increasing rapidly in Australia over the last decade due to its availability and climate-friendly attributes. Solar energy is free from green house gas (GHG) emission and plays a key role in developing a sustainable power system for the future. However, the intermittent nature of solar energy creates a number of potential challenges in integrating large-scale photovoltaic (PV) with the grid. Voltage fluctuation, voltage management, harmonic distortion, demand management, and load rejection are the major potential issues concerning the application of photovoltaic in Single Wire Earth Return (SWER) network. This paper presents the impacts of varying PV penetration levels on different SWER networks. Of particular interest was the adverse affect on voltage instability of the network with varying PV penetration. Simulation results shows that voltage rises across the network would exceed regulatory standards with the high penetration of PV in SWER networks.