Grid Tied Systems
A grid-tied electrical system, also called tied to grid or grid tie system, is a semi-autonomous electrical generation or grid energy storage system which links to the mains to feed excess capacity back to the local mains electrical grid. When insufficient electricity is available, electricity drawn from the mains grid can make up the shortfall. Conversely when excess electricity is available, it is sent to the mains grid.
When batteries are used for storage, the system is called battery-to-grid (B2G), which includes vehicle-to-grid (V2G).