Role of Charging/Discharging in the Integration of EVs to Grid as Intermittent Energy Sources

An extensive use of electric vehicles (EVs) is evolving as an important solution to counter environmental pollution, rapid exhaustion of fossil fuels and insecurity caused by fluctuations in the price of petroleum products in the international market. The integration of EVs to the grid is required for the future enhancement of the transportation system. Grid integration of EVs also presents an interesting opportunity to solve the issues faced due to intermittent nature of renewable energy sources (RES) connected to the grid. The charging of EVs must be well coordinated with the grid otherwise it will result into an uncertain large electric load, causing peak-load and grid issues. Thus, the EV technology presents opportunities as well as challenges to the electricity grid. The development in EV technologies, battery systems, and different charging methodologies are reviewed with special focus on vehicle to grid technology as a solution to many grid issues, especially with RES connected to it. This paper presents a brief overview of these issues and various solutions.