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Solar news: week of July 27th, 2018

In this week’s Solar News Roundup, Vermont utility Green Mountain Power reports that their virtual power plant program saved half a million dollars during the recent heatwave, and Duke Energy introduces a community solar program available to South Carolina customers.

Green Mountain Power’s virtual power plant helps the utility save during recent heat wave

Green Mountain Power (GMP), a utility in Vermont, began an innovative program last year that dramatically cut the price of a Tesla Powerwall battery installation for homeowners in their territory. The program allows customers to lease Powerwalls from the utility company for a small monthly payment and stipulates that GMP can pull power from the batteries (around 500 batteries total) at times of need. This occurred earlier this month during a period of high demand, as a heat wave moved through the northeast United States. Their Powerwall network performed more than adequately.

In the first week of July alone, GMP pulled electricity from the network of Powerwalls several times. Taking previously stored energy from the batteries allowed GMP to rely less on purchased electricity during the heatwave. The utility estimates that they saved almost $500,000 dollars during the heatwave.

These Tesla Powerwalls save GMP money not only because they buy less electricity overall, but also because they avoid excessive purchasing during the peak usage hours. New England utilities pay a payment each year to the bulk transmission system in the region and that payment is determined by each utility’s usage during the hour of the year when the most electricity was being used. So far, that peak usage hour is 5 to 6 pm on July 5, right in the middle of the period of time when GMP was pulling energy from batteries instead. By predicting peaks in usage, utility operators can continue to use the Powerwall network to avoid paying peak electricity rates as well as reduce their yearly bulk transmission charge.

GMP expects much more return on their Powerwall investment over its lifetime. “Unlike when you build poles and wires, where you have to build them and function with them but they don’t return any value, this actually pays for itself plus more,” said GMP’s vice president and lead innovation officer, Josh Castonguay. “Over the life of the program, we anticipate returns of over $2 to $3 million.”

Duke’s community solar program kicks off in South Carolina

Duke Energy Progress, a subsidiary of Duke Energy serving customers in South Carolina, officially launched their new Shared Solar Program this week. Available to all qualified Duke Energy Progress customers in both the residential and non-residential sectors (including multifamily and rented homes), the new program will get energy from the Whitney M. Slater Shared Solar Facility in Dillon County.

Customers will pay a monthly fee of $6.25 per kilowatt (kW) of energy used, on top of joining fees. As with many community solar programs, these monthly fees support the operation of the Dillon County solar facility. Additionally, qualified low-income customers of the utility will have their application cost and initial fees waived, valued at around $120.

Subscription to the Shared Solar Program will save Duke customers money, as well as help promote solar energy around the state and country. “We estimate that residential customers will earn back their initial payment in credits from the solar array in three years,” remarked Kodwo Ghartey-Tagoe, the state president for Duke Energy in South Carolina. “Customers are not only saving on their electric bill, they are directly supporting a renewable energy future in South Carolina for generations to come.”

Solar in South Carolina continues its accelerated growth with the help of projects like the Shared Solar Program. In 2017, the state moved up to number eight in the country for installed solar during the calendar year. Duke Energy has also already provided over $50 million in rebates for customers going solar in its South Carolina territories.


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