original_query: What is the definition of vehicle-to-grid (V2G)?
query: What is the definition of vehicle-to-grid (V2G)?
answer: Vehicle-to-grid (V2G) is a system where plug-in electric vehicles (PEVs) communicate with the power grid to provide demand response services by returning electricity to the grid or throttling their charging rate.  This allows EVs to store and discharge electricity from renewable sources.