Numerous North American utilities are integrating growing numbers of investor-owned photovoltaic distributed generation (PV-DG) plants into their distribution systems to comply with state-mandated Renewable Portfolio Standards (RPS). Given the fact that distribution systems have been designed to be operated in a radial fashion, interconnection of PV-DG may lead to significant impacts on planning and operations that need to be studied to identify mitigation measures and ensure seamless integration. The purpose of this paper is to discuss impacts of PV-DG on power distribution systems planning and operations, including those of steady state and dynamic nature, with emphasis on utility-scale PV-DG. This paper also discusses mitigation measures to address these impacts and presents results of analyses conducted on real distribution feeders and other ramifications of their increased use in distribution networks, especially urban ones.