Net metering is the mechanism by which you get credit for the power your solar system produces. Whenever the sun is shining on them, they are producing power. If you are also using some electricity, you will be credited for the difference. And then, when the sun is not shining and you are using electricity, that will also count against your credits. Every month, your credits roll over to the next month. And then, at the end of the year, on what's called your anniversary date (which you pick when your system is installed), you will receive a refund from your utility company for any remaining credits. Note that you will pay for your electricity at the retail rate, but will be paid for credits at the end of the year at the wholesale rate. So, it really doesn't pay to grossly oversize your system expecting to make money off the utility company. (Also, you will only receive state incentives for up to 110% of your electricity needs for systems sited on your property and 100% of your needs for community distributed generation systems -- see below.)
It's also important to note that every month you will continue to be charged a line fee by your utility. This is currently roughly $12-$15. So, even if your panels provide 100% (or more) of your electricity usage, you will be charged this fee. (Think of it as the cost for the electric utility to maintain all of the lines and act as your system's battery, ensuring you have power when the sun doesn't shine and when your system isn't providing all the power you need.)
Homeowners and even renters can now take advantage of solar electric systems -- even if their property gets little or no sun. In the fall of 2015, NY State expanded regulations allowing residents to take advantage of solar systems situated off-site, as well. So-called community distributed generation greatly expanded solar electric systems to people whose sites were less than ideal for solar, including renters. It works just like having a system on your property and having the power "net metered" so that you receive credits for all the power the panels produce, even though they're on someone else's property. And if you move to another apartment or house in the same utility zone, you can take your system (or at least the solar credits) with you!
Last updated June 12, 2018