Duke Energy Carolinas residential VPP economics

Duke Energy Carolinas (DEC) serves the western and central Carolinas, including Charlotte, Greensboro, Durham and Greenville–Spartanburg. Unlike the utilities in our California, New York and New England deep dives, it is vertically integrated: it builds and runs the power plants, owns the grid and serves every customer directly. There is no regional wholesale market like PJM or CAISO in the Carolinas, so the value of a flexible kilowatt shows up in Duke’s own rates and program credits rather than in a market price.

The split that matters here is the state line. The North Carolina Utilities Commission (NCUC) and the Public Service Commission of South Carolina (PSC) each approve DEC’s rates, net metering rules and pilots for their side of the territory, with the NC Public Staff (Public Staff) and the SC Office of Regulatory Staff representing customers. That is why PowerPair exists only in North Carolina while Battery Control is offered in both states.

Duke runs one of the largest demand response portfolios in the Southeast, with nearly 500,000 customers in its programs across the Carolinas (Duke Energy). Almost all of it is event-based demand response, where Duke cycles a thermostat, water heater or battery on peak days. The orchestration is Duke’s own; no third-party aggregator sells this capacity into a market.

Every deep dive on this site follows the same template, but each has one feature that changes how its economics read. For Duke Energy Carolinas it is the clock. Most VPP programs we cover chase a summer evening peak, when air conditioners run and solar output fades. DEC’s system is increasingly winter-peaking, with its hardest hours on cold weekday mornings when heat pumps and electric resistance heat run flat out before sunrise.

The history explains the design. On December 24, 2022, during Winter Storm Elliott, Duke ran rolling outages that reached about 500,000 customers, roughly 15% of its Carolinas customers (Duke Energy); the outages began shortly after 6 a.m. (FERC and NERC), and about 94,900 were in South Carolina (SC Office of Regulatory Staff). On January 27, 2026, DEC set a new winter record of 37,308 MWh in one hour (WFAE).

Three things follow for a battery. First, a winter morning event must be served from charge taken overnight, from the grid. Second, the battery that sits full for backup is exactly what Duke wants on a December morning, which makes the event program a better fit for most homes than daily arbitrage. Third, in winter the multi-asset partner that matters most is not solar but the heat pump: a Power Manager thermostat that pre-heats before 6 a.m. moves the same morning load as several kilowatt-hours of storage, and it costs far less.

That is the multi-asset lesson at a Duke address. Solar and a battery work together on summer evenings, much as they do elsewhere. In winter, the useful pairing is the battery with the heating system, both steered by Duke’s events, while the roof sits idle until mid-morning.

All $789 a year comes from one payer, Duke, and the battery brings about $624 of it. A Powerwall 2, rated lower, would earn about $23 a month instead (Duke Energy). Thermostat events run in both seasons, with winter dispatch starting as early as 6 a.m. (Greater Grid). Duke’s EV Complete Home Charging Plan pilot offers a flat $19.99 a month for up to 800 kWh with up to three events a month (EV Charging Help), which can be worth more than the credit for high-mileage drivers.

Batteries are the most valuable single asset in nearly every program we cover, but VPP growth at scale depends on several assets working together at one site. Solar alone does little for a peak that falls before sunrise or after sunset. A battery charged from midday solar should, in principle, be charged for free.

At Duke, the answer depends on the net metering rider. Under the Net Metering Bridge (Rider NMB), solar exports net against purchases month by month at the flat residential rate, so a stored kWh is worth no more than an exported one. Under the Residential Solar Choice rider (Rider RSC), excess is credited at 4.53¢, but netting happens within each time-of-use period every month, and the home must be on a time-of-use rate (Solar Learning Lab). Midday summer solar therefore offsets off-peak use worth 10.3¢ before anything is exported.

Duke sits in the middle of the chart: a stored solar kWh keeps about 12¢ of the 23.5¢ peak. But the grid beats it. Charging at the 7.4¢ discount price keeps about 15¢, so a Duke time-of-use home does better leaving summer solar to offset off-peak use and filling the battery between 1 and 6 a.m. In winter, solar lands in the 11 a.m.–4 p.m. discount window, the cheapest hours of the day, and the next peak is the following morning. Duke’s rate design steers the battery toward the grid, not the roof.

PowerPair splits buyers into two cohorts (NC Clean Energy Technology Center). Cohort A takes Rider RSC and a time-of-use rate and controls its own battery; in our example that is worth about $415 a year. Cohort B takes the Net Metering Bridge and signs a 10-year Battery Control agreement, worth about $624 for a Powerwall 3. Sources disagree on which cohort still has room in DEC (Southern Energy), and PowerPair reports less than 3% of capacity left (PowerPair).

The best documented Duke case, PowerPair with Battery Control, pays back in about 18.1 yr, and Cohort A in about 27.2 yr. Neither clears ten years, and neither counts backup power, which is the main reason many Carolinas buyers add a battery after Winter Storm Elliott. A buyer who misses PowerPair loses almost a third of the battery’s cost in one step.

Financing at Duke turns on the same federal gap as everywhere else in 2026: a homeowner who buys gets no residential credit, while a leasing company can still claim the commercial credit. Because the Bridge leaves little bill savings, the Battery Control credit of about $624 a year is the cash flow that has to cover a loan or lease payment.

Related: the SCE residential deep dive for a solar-led battery case, the Portland General Electric residential deep dive for another utility without an organized market, the Mass Save residential deep dive for a net metering contrast, and the Duke Energy Carolinas C&I deep dive. To run other equipment, use the Residential VPP Calculator.