What is net metering?

With net metering, the solar system is connected to the grid through a meter that records energy flowing in both directions. When production exceeds consumption, the surplus is fed into the grid; when you are not producing, for example at night, you draw energy from it. At the end of the billing period, the kilowatt-hours you exported are offset against those you imported, and you are charged for energy only on the difference.

The grid therefore acts much like a "store": surplus midday production can cover consumption at other times, without batteries. Offsetting usually applies only to the energy itself; other charges on the bill, such as network fees, may still apply.

The rules differ from country to country and change over time. In many markets, simple net metering is being replaced for new installations by schemes where the surplus is paid for in money rather than offset (net billing), which makes self-consumption at the time of production, or battery storage, more worthwhile.

Before sizing a system, check the scheme that applies to your own connection today. A common mistake is designing a solar system around older rules or someone else's experience.