Virtual power plant (VPP) platform profile
Generac Concerto and ecobee: devices, DERMS and measured results
How Generac combines batteries, generators and ecobee thermostats with its Concerto software, and what an independent evaluation found.
VPP Economics has no affiliation with, sponsorship from, or endorsement by any utility, aggregator, platform, or device maker named here.
The short answer
- Generac sells both the devices and the software. Its Generac Grid Services unit runs Concerto, a distributed energy resource management system (DERMS) and VPP platform it got by buying Enbala in 2020 (Generac). Generac also makes home batteries and standby generators and owns ecobee, the smart thermostat maker.
- Concerto is utility-grade and vendor-neutral. Dominion Energy Virginia chose it as its single, comprehensive DERMS, integrated with its distribution management system (Generac Grid Services).
- The ecobee fleet is the measurable piece. An independent evaluation found ecobee’s Grid Resiliency service delivered 108 MW in summer 2025, averaging 0.65 kW per device, with an estimated 2.8 GW of potential (ecobee).
- It covers the full spectrum. Generac runs event-based thermostat programs, multi-year battery contracts with voltage support and, overseas, frequency regulation.
Where Generac fits
Highlighted boxes are the roles this company plays; the green bar shows where its programs sit from demand response to an orchestrated VPP.
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What Concerto does
Concerto forecasts available capacity in real time and dispatches mixed fleets, from home thermostats and EV chargers to commercial process loads and utility-scale renewables, through an open interface (Generac Grid Services). Utilities can license it to run their own programs or buy a full-service performance contract where Generac recruits customers, installs and connects devices, dispatches them and handles settlement, and the utility simply pays for the capacity (Generac Grid Services).
Dominion Energy Virginia uses Concerto to dispatch distributed resources for reliability and to enroll them in programs or the PJM wholesale market, including real-time voltage support at specific locations (Generac Grid Services). Arizona Public Service hired Generac for a five-year program, starting in 2023, that aggregates PWRcell home batteries for system capacity, feeder-level capacity and voltage support, with Generac also handling customer acquisition and measurement (Generac). Generac was also one of Southern California Edison’s Power Flex VPP providers (pv magazine USA).
Outside the U.S., Concerto has run AGL Energy’s VPP in Australia, Alectra’s in Canada, and an RWE VPP in Germany that provides secondary frequency reserve from generators, combined heat and power, industrial loads and batteries (Generac Grid Services).
ecobee Grid Resiliency: delivered versus potential
Megawatts (MW). Summer 2025 results from an independent evaluation, with the evaluator’s estimate of untapped potential
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ecobee: thermostats at fleet scale
Grid Resiliency is part of ecobee’s eco+ service and lets grid operators reduce demand across all enrolled homes, alongside traditional utility programs. Across 11 events, more than 143,000 enrolled devices averaged a 0.65 kW reduction, with peaks above 1 kW per device and 73% average participation (ecobee). One ERCOT event alone mobilized 78.1 MW, and an ERCOT Emergency Response Service enrollment through Leap delivered a median 99% of nominated capacity (ecobee).
ecobee passed 5.25 million connected homes in mid-2026 (Generac earnings call). On the commercial side, Generac and CPower announced in April 2026 a program to enroll commercial generators and other distributed resources in PJM demand response (pv magazine USA).
What it means for program design
License or outsource
Concerto can run as a utility DERMS or as a full-service capacity contract. The second shifts recruitment and performance risk to the vendor.
0.65 kW is a planning number
Independent evaluation of a large thermostat fleet gives a defensible average for summer peak programs.
Hardware makers can aggregate
Generac’s devices, ecobee’s fleet and Concerto let one company enroll, dispatch and verify, much like Tesla on the battery side.
Method and caveats
Figures are company-reported, checked October 15, 2026. ecobee results come from a Demand Side Analytics evaluation commissioned by ecobee. Older contract details (APS, SCE) come from Generac announcements at signing.