Grid-Connected Small Solar Electric Systems
A grid-connected small solar electric or photovoltaic (PV) system receives back-up power from a utility's grid when the PV system is not producing enough power. When the system produces excess power, the utility is required to purchase the power through a metering and rate arrangement.
Net metering is the best arrangement. Under this arrangement, the power provider essentially pays you retail price for the electricity you feed back into the grid. See Estimating Energy Cost Savings for a Net-Metered Photovoltaic System.
For more information, see Connecting Your System to the Electricity Grid.