In order to ensure the longevity of electricity supply for human living and comfort on earth, electric grid should be an intelligent, well established, automated and more importantly environmental friendly energized network. Demand crises and CO 2 emissions all over the globe have led to deploy more number of Renewable Energy Sources (RESs). The Smart grid technologies are becoming the most important entities in the electric power sector, in terms of modernizing the legacy grid with high-level penetration of RES and maintain reliability and quality of electric power. Exploitation of advanced technologies to optimize the power usage and reduce greenhouse gasses emission is inevitably the main concerns for the electric utility. RES integration brought so many issues along with their advantages. Plug-in Electric Vehicles (PEV) during last decade has shown drastic market growth with reduced cost and higher energy density storage. Bulk number of PEV integration with uncoordinated charging schedule is a big hurdle to power system operation. This paper mainly focuses on the challenges and issues that will arise in Smart Distribution System (SDS) because of high-level penetration of both RES and PEV. The impacts of intermittent PES and uncoordinated PEVs on distribution network stability are discussed. Exploitation of PEV as a storage unit with bi-directional power flow is discussed to mitigate solar and wind power generation fluctuations. Real time data from Danish distribution network is used for case study to demonstrate PEV utilization for grid ancillary support. © 2018 the Author(s). All rights reserved.