It decreases the amount of electricity drawn from the grid, saving the homeowner money not only on electricity charges, but also delivery, regulatory fees and tax.
Any excess electricity produced is sent out to the grid for monetary credits (electricity, delivery and regulatory) as if the owner of the system had sold the electricity to the grid, for the same price they bought it at during the time generated.
Solar owners can now take advantage of variable rate plans. As of 2024, net metering customers can choose to be billed on a "time of use" basis. Solar energy is generated during peak hours 9am-6pm. When the energy from the grid is the most expensive. They can now get a higher price for the energy they produce. Therefore, they get generation credits at higher rates during peak hours and draw that energy back up at night when it is cheaper.