Net metering is the billing process that allows grid-tied solar system owners to be credited for the amount of electric they are sending back out to the grid. Any excess of electric that is produced during the day that you are not using is being sent back out into the grid, running your electric meter in reverse. When there is a need for electric when you solar system is not producing, such as nighttime, you pull electricity from the gird, running your meter forward. At the end of the month you are billed for your net usage.