During the day, your Solar PV System is producing energy and feeding it directly into your home. When your system is not producing electricity at night, you will receive electricity from the grid as normal. Any excess energy generated during a given billing period is sent back to the utility company, which builds a ‘credit’ for you. This excess energy is reflected on your monthly bill as a credit that further reduces your bill.
Some utility companies do not offer a Net-Metering option but allow a solar array to be installed on a separate meter. Under this type of connection you will sell all of the energy produced by the solar array rather than using it in your home. Every month your utility company will mail you a check for the electricity you generated during that billing period.
Grid Tied vs. Off-Grid
Depending on where you live, and what you expect from your solar system you will have two choices regarding what type of solar system you will install: grid-tied or off-grid.
A grid-tied system connects directly to the utility grid, and depending on how your utility company is set up, you will either use the power you generate via net-metering or sell it to your utility company via buy-all/sell-all. The grid serves the same purpose as batteries in an off-grid system as it is the storage for your power when you are not using it.
An off-grid solution is appropriate for a home where the grid is inaccessible due to remote location. A collection of batteries is necessary for an off-grid system to store reserve power. This stored power can then be used at night as well as on days where weather conditions may inhibit the output of the solar array, providing a consistent source of power.
There is a third option that combines the pros of grid-tied and off-grid systems; a grid-tied with a battery backup system. If you live in an area with frequent power outages, you may be a perfect candidate for this type of system. A battery backup system gives you peace of mind knowing that your home will never lose power in the event of a grid-wide power outage.