FAQ: What is the “solar adder”?

Vermont state law requires that utilities provide at least a minimum level of value for solar net metering. The way the law is put into effect depends on the utility involved and its rate structure.

If your utility is Green Mountain Power, then the solar adder functions as bonus credit on your electric bill for each kWh of solar you produce. You receive the solar adder for the first 10 years of your solar array.

The size of the adder depends on when your solar array goes into operation and how large it is. If your solar array went into operation prior to 2015, you get 6 cents per kWh of bonus credit above and beyond regular net metering for your 10-year adder period. Those whose solar array is installed in 2015 get an adder that varies by the size of the array: arrays of 15 kW or smaller (three or fewer Solaflect PV Trackers) get 5.3 cents per kWh of solar adder for their 10-year adder period, while arrays that are larger than 15 kW get 4.3 cents per kWh.

If GMP changes its residential rates, then the solar adder will change for those who go solar after that point in time. If GMP’s rates rise, then those who go solar after that change will receive a smaller solar adder for their 10-year adder period. This is one consideration to keep in mind if you are trying to decide between going solar sooner rather than later. The longer you wait, the greater the risk that the adder will be smaller or even gone altogether. But once you go solar, you have locked in the current adder for your 10-year adder period. Those who went solar in 2015 instead of 2014 lost out on several hundred dollars worth of adder value because their adder is down from the 6 cent version available in the earlier year.

See more FAQs here.

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