| GreenPoint Clean Energy | Sharon, CT

Net Metering, Battery Back-Up, and Selling Back to the Grid

What is net metering?

Net metering allows owners of a renewable energy generator, such as a wind turbine or solar photovoltaic array, to benefit from the use of every single kilowatt (kW) of power that is generated. At times, solar arrays and wind turbines produce more power than is actually needed. At other times your consumption will exceed your system’s production and you will have to use power generated by your local utility. In simple terms, net metering sends your surplus power back to the grid, and gives you credit for electricity purchased at unproductive times.

How does net metering work?

Your power company will provide you with a meter that is capable of registering electricity flow in either direction. Your wind turbine or solar photovoltaic array is connected to this meter (tied into the grid) when installed. Net metering begins automatically. When you are using electricity from your local utility company, your meter spins forward, increasing the number of kilowatt-hours for which you will be billed at the end of the month. When your system is generating more electricity than needed at a given time, your meter spins backwards as the excess electricity flows out into to the grid, decreasing the number of billable kilowatt-hours.

What about selling back to the grid?

If you consistently produce more electricity than you use, the meter can spin backwards into negative territory. Most utility companies, including those in Connecticut and New York, allow monthly rollover of excess - electricity produced by a solar array in the summer can spin the meter backwards into negative territory, where it might remain until winter when you again consume more electricity than you produce. Settlement of excess, or selling back to the grid, is only performed once a year. If your meter reads negative when your utility company performs it’s annual settlement – if you have produced more electricity than you have consumed over the course of the year – you can sell that electricity back to the utility company at its wholesale rate. The utility company will credit your bill, or you can elect to have a check sent to you.

Will I need a battery storage system?

Battery storage systems connected to renewable energy sources act as a back-up power source much like a gasoline-powered generator. You don’t need to store the excess electricity you produce in batteries, as the net metering system gives you the benefit of every kilowatt of energy produced. Battery storage systems are beneficial as a back up if the power goes out but are not required for an effective solar or wind system.