Grid Tie in:
A grid tie inverter changes DC to AC and safely sends your renewable energy back to the utility company which spins your meter backwards reducing you electric bill and in cases the electric company owing you money. In this type of system, the utility grid acts as an infinitely large battery bank storing your generated power for use by someone else down the line. The following illustration shows how the typical solar or wind electrical system is configured to send power to the grid:
A Grid-tie system consists of either  a solar array or wind turbine and grid tie inverter. The main service entrance to the building and the Net kWh Meter are already installed on existing buildings if utility power is present. A user-friendly inverter includes all components necessary to make a grid connect system installation simple and code compliant.