Below is an actual copy of a power bill from Pepco of one of our clients after we installed solar panels on their roof. Keep in mind, every utility has a slightly different way of presenting their charges, but this is typical.
Pepco utility bill with solar:
You can see that Pepco displays the energy consumed by the building (537 kWh) together with the energy produced by the solar system (424 kWh). Pepco will only charge for the net different, being 113kWh.