If you’re tied to the grid, then you simply take electricity from the utility. This happens whenever you are consuming more electricity than your solar system is producing – such as at night or during cloudy weather. When the sun is shining, however, and you are producing more power than you’re consuming, the solar system will feed the excess electricity back into the grid, causing your meter to spin backward. Each month, your utility net‐meter may spin backward and forward on a daily basis, but your monthly utility bill will only show the “net” usage that occurred.
This is called “net metering” and it allows you to achieve a “net zero” bill by selling back the power that you use at a retail rate. If you produce more power than you use each month, the credits will carry over for later use. Afterward, if you still have a credit leftover, the utility may pay you for the excess power you produced, or you may elect to carry credits forward indefinitely for future usage.