Net Metering (or net billing in some jurisdictions) allows you to generate as much electricity as you consume on an annual basis. If you produce more than you consume at any given time, you can store that electricity in the grid as a credit on your next electricity bill. At times when you will be consuming more power than your solar system is producing (like at night or when it is dark), you use the credits that were previously generated before incurring any new electricity costs.
The best part about net metering is that is available almost everywhere and you can start net metering whenever you want, subject to an interconnection screening by your local utility.