Net-metered customers generally are credited for the electricity they sell to the grid, with their electric meter essentially spinning backwards to provide a credit against the electricity that these customers must buy from their electric utility at night or during other periods when their electricity use exceeds their system’s output. Customers are only billed for their “net” energy use.
That means that when rooftop solar or other DG customers generate electricity, they avoid paying for the utility’s power, which is fair because they did not use it. But, they also avoid paying for all of the fixed costs of the grid that delivers power when they need it and/or takes the excess power they sell back to the utility.
You can download the PDF here.