Heat pump water heaters: the economics of leveraging as a Virtual Power Plant asset
A tank of hot water is stored energy, just like a battery. Heat it a few hours early and it can coast through the evening peak with nobody noticing, which makes the water heater the easiest appliance in the house to flex. Utilities have used that for decades with radio switches on resistance tanks. Heat pump water heaters change the math: they use far less power, have more electronics, and can join programs that range from a $1.50 monthly credit to daily load shifting to selling grid services. This article compares 8 utility programs, explains why the most efficient tanks have the least to shed, and covers the setup details that decide whether it works. Heatpump Economics has no affiliation with, sponsorship from, or endorsement by any utility, aggregator, or water heater maker named here.
The short answer
The best water heater programs pay more than thermostat programs, and cost you less comfort. Over 10 years, one enrolled water heater earns $130–$1,300. The daily-shifting programs in California pay the most; flat event programs pay $130–$300.
They vary far more than thermostat programs. Designs run from a one-way switch a few mornings a year, to a new schedule every day, to Hawaii, where water heaters sell fast frequency response to the grid.
Efficiency cuts both ways. A heat pump water heater draws about one-eighth the power of a resistance tank, so it sheds less, roughly 85–225 W per event versus 320–375 W. Programs that pay per device treat both the same; programs that pay per kW or kWh favor resistance tanks.
The setup decides the result. A mixing valve, a working connection, and a schedule that doesn’t trigger the backup resistance element matter more than the check.
8
Utility water heater programs priced, in 7 states
$130–$1,300
10-year value for one enrolled water heater
0.20 kW
Measured peak cut per heat pump water heater on a daily schedule
4%
Share of events customers overrode in a large Northwest pilot
Why a water heater makes a good battery
A thermostat event trades comfort for money: the house warms or cools while you wait. A water heater event usually trades nothing you can feel. The tank holds 50 gallons or more of hot water, so the utility can heat it before the peak, pause it during the peak, and let it recover afterward. In the Bonneville Power Administration’s (BPA) Northwest pilot, customers overrode winter events only 4% of the time, about 10% ever used an override, and 80% said they were very satisfied (BPA).
Two details stretch the “battery.” A bigger tank stores more (ENERGY STAR). A thermostatic mixing valve lets the tank run hotter than the water at your tap, so it holds more heat without scalding anyone; Sacramento’s SMUD uses one to soak up excess solar power (SMUD), and SCE requires one on heat pump water heaters in its program (SCE). ENERGY STAR says connected electric water heaters can shift up to 1 kW per event by pre-heating (ENERGY STAR).
Four ways utilities use your water heater
Our heat pump VPP article found that nearly every thermostat program is event-based demand response, whatever it is called. Water heater programs are different: they cover the whole range, from one-way load control to a grid resource dispatched within seconds.
The utility pauses the tank on peak days. Florida Power & Light (FPL) can interrupt a conventional tank up to 4 hours a day for $1.50 a month (FPL). Duke Energy cycles tanks off for up to 4 hours on winter mornings (Duke Energy). PSE calls 2–4 hour events up to 200 times a year (PSE).
2. Daily load shifting
Every day, the program heats water before the peak and coasts through it. PG&E’s WatterSaver runs one event daily, typically 2–9 p.m. or noon to midnight depending on your rate (WatterSaver). SCE’s SmartShift pays year-round (SCE).
3. Grid services
Hawaiian Electric pays per kW per month for fast frequency response, adding load, and cutting load, through partner Shifted Energy (Hawaiian Electric). Its EnergyScout program is replacing nearly 20-year-old switches with 27,000 Aquanta controllers for about 11 MW plus fast frequency response (Aquanta).
4. Off-peak storage
Rural cooperatives have long run big tanks on off-peak rates. MiEnergy controls storage water heaters 8.5 hours a day in summer and 14 in winter (MiEnergy); Minnkota pays $125–$300 rebates for off-peak tanks (Minnkota), with an off-peak rate roughly half the standard rate (DOE).
Eight programs, one water heater
To compare them, we add each program’s sign-up credit to 10 years of payments at today’s rates for one tank. We left out upfront equipment rebates, which are covered in our state pages, and programs that don’t publish their pay.
Ten-year value of one enrolled water heater, by program
Swipe to see the full chart →
Sign-up credit plus yearly pay for 10 years at today’s rates. Sources: SCE (the same page also lists a $50 sign-up and about $60 a year, so we show a range), PG&E WatterSaver, SMUD, Austin Energy, Duke Energy, PSE, FPL ($1.50 a month), Dominion Energy ($40 after the first year, then $10 a year; closed to new enrollment).
Thermostat reference: the typical program in our heat pump VPP comparison. Upfront equipment rebates are not included.
The pattern is clear: programs that shift every day pay more than programs that call a few events. SCE pays $100 to enroll plus $5 to $10 a month (SCE); PG&E pays $50 plus $5 a month, as long as the heater takes signals at least 14 days a month (WatterSaver). The event programs in Florida, Washington, the Carolinas, and Virginia pay $10 to $25 a year. Dominion’s was the strictest, requiring participation in 75% of event hours for $10 a year after the first, and it has closed to new enrollment (Dominion Energy).
Compared with the thermostat programs in our heat pump VPP comparison, where a typical program is worth about $350, SCE and PG&E pay roughly two to four times as much. The rest pay about the same or less.
The efficiency paradox
A heat pump water heater moves heat from the air into the tank instead of making it with a resistance element, so it uses a fraction of the power. The grid benefit starts there: switching from uncontrolled resistance tanks to connected heat pump water heaters cut evening peak load about 90% in a Pacific Northwest National Laboratory study (DOE). But once the heat pump is installed, there is less left to shed.
The efficiency paradox: less power used, less power to shed
Swipe to see the full chart →
Power while heating: a 50-gallon resistance tank draws about 4,500 W; a similar heat pump water heater about one-eighth as much (ACEEE). Shed per event: average reduction per tank during 3-hour winter and 4-hour summer sheds in the Bonneville Power Administration’s CTA-2045 pilot, 145 heat pump and 86 resistance water heaters (BPA).
In the BPA pilot, a heat pump water heater shed 223 W on winter mornings and only 85 W on summer evenings; a resistance tank shed 347–374 W (BPA). The American Council for an Energy-Efficient Economy (ACEEE) puts the typical shift at about 500 W for resistance tanks and less than half that for heat pumps (ACEEE).
How a program pays decides who wins. Most programs above pay per device, which is generous to heat pump owners: PG&E’s $60 a year against a measured 0.20 kW works out to about $300 per kW-year, far more than thermostats earn and on par with, or above, what most home battery programs pay per kW (Battery Economics). Programs that pay for measured power or energy do the opposite. Portland General Electric’s earlier water heater pilot paid $1 per kWh reduced during events (PGE), and Hawaiian Electric pays per kW enrolled (Hawaiian Electric). On those terms a resistance tank earns more. That is one reason some cooperatives still give members large resistance tanks for off-peak programs (MiEnergy), even though a heat pump water heater would cut their energy use by more than half (ACEEE).
A day on a load-shifting schedule
Daily shifting sounds simple, but the details matter for heat pump models. The heat pump heats slowly, so the program has to start early, and if it asks for too much too fast, the backup resistance element can switch on and use more energy than it saves.
A day on a daily load-shifting schedule
Swipe to see the full chart →
Illustrative profile, not metered data. Schedule and averages from PG&E’s WatterSaver: one daily event, load up 2–4 p.m. and shed 4–9 p.m. for most time-of-use customers, with about 0.64 kWh added before the peak and 0.50 kWh and 0.20 kW removed during it (WatterSaver evaluation, program manual).
PG&E’s evaluation of WatterSaver shows the trade-offs. Its most aggressive “advanced load-up” signal cut peak demand about 0.20 kW per heater, but it needs a mixing valve and a setpoint below 140°F, can trigger the resistance element, and saved customers only $7 to $32 a year on their time-of-use bills. The program dropped its “grid emergency” signal because of the risk of running out of hot water, and it reports that some of the load comes back within a few hours of each event (WatterSaver evaluation).
Smaller 120-volt heat pump water heaters, which plug into a standard outlet and usually have no resistance element, avoid the backup-heat problem. In a 2024 California field test they shifted an average of 39.4% of their load away from peak hours and cut operating costs 24.2% (New Buildings Institute). But getting them connected was harder: in the follow-up study, fewer than half of eligible customers opted in and 17% of module installations failed (LBNL).
How your water heater connects
Before you can join, the program has to reach the tank. There are four common routes.
A standard plug-in port (CTA-2045)
Many heat pump water heaters have a slot for a small module that speaks the CTA-2045 standard over cellular or Wi-Fi. Programs such as WatterSaver and PSE provide the module free or at low cost (WatterSaver, PSE). Washington, Oregon, and Colorado require new electric storage water heaters to have the port (Friedrich); Oregon’s rule dates to January 1, 2022 (Oregon law).
The maker’s Wi-Fi app
Some programs talk to the manufacturer’s cloud. PSE supports Rheem’s Wi-Fi models (PSE), Dominion required a Wi-Fi heat pump water heater (Dominion Energy), and Rheem customers in California and New York can enroll with Renew Home and OhmConnect in the EcoNet app (Rheem).
An add-on controller
A box on the power supply can switch any electric tank on and off and learn its patterns. Hawaiian Electric is installing 27,000 of them for free, with a monthly bill credit (Aquanta). They work best on resistance tanks, which a switch can control cleanly.
A utility switch or timer
The oldest route: a one-way radio switch or timer that cuts power at set times. Duke, FPL, and many cooperatives still use them (Duke Energy, FPL). Cheap and reliable, but the utility can’t see what the tank is doing, so it can’t sell much more than peak cuts.
Connectivity can also pay upfront. Xcel Energy in Minnesota pays $400 for an ENERGY STAR heat pump water heater, or $500 if it can enroll in demand management (Xcel Energy), and ENERGY STAR’s NextGen new-home program requires heat pump water heaters to be connected or have a CTA-2045 port (ENERGY STAR).
Programs we couldn’t price
Portland General Electric (PGE) offers bill credits all year through its smart water heater pilot but doesn’t publish the amount (PGE). Rheem’s program with Renew Home pays in cash or gift cards per event, without a published rate (Rheem). Hawaiian Electric pays Oahu customers $5 per kW per month for fast frequency response, $3 for adding load, and $2 for cutting it; the total depends on how many kilowatts a partner enrolls for your tank (Hawaiian Electric). Duke Energy Florida’s EnergyWise Home pays up to $141 a year across heating, cooling, and water heating, without a separate water heater figure (Duke Energy).
What’s coming
The biggest change is equipment. Under the new federal water heater efficiency standard, ACEEE expects three-fourths of new electric water heaters to be heat pumps by 2029 (ACEEE). California’s Energy Commission is writing flexible-demand appliance standards that let devices schedule, shift, or curtail their use with consumer consent (California Energy Commission). And Hawaiian Electric’s controller rollout runs through 2027 (Aquanta). Expect more tanks that arrive connected, and more programs that pay for daily shifting rather than a few events.
Not just water heaters
A water heater is one piece of a flexible home. The same program or VPP may also call on a smart thermostat and heat pump, a home battery, or an EV charger. See our heat pump VPP article for thermostats and the difference between demand response and VPPs, Battery Economics for home batteries, and Drive Economics for EVs. In future case studies, we’ll combine these devices and model what a whole home earns in specific regions.
Who this fits
Worth enrolling: almost anyone with a connected electric tank. Events are rarely noticeable, and you can override them.
Especially worth it: SCE and PG&E customers on a time-of-use rate, where daily shifting pays the most, and anyone buying a new heat pump water heater where a utility pays extra for a connected model.
Think twice: large households that run the tank hard in the evening, and heat pump models without a mixing valve on programs that pre-heat aggressively. Both raise the chance of cold showers or backup resistance heat.
Questions to ask before enrolling
Is this a few events a year, or a daily schedule? Which hours?
Does my model qualify, and how does it connect: a CTA-2045 module, the maker’s Wi-Fi, or a controller?
Will the program pre-heat, and do I need a mixing valve for it?
Can the schedule switch on the backup resistance element?
Do I have to stay connected or take part in a minimum share of events to be paid?
Does it stack with my time-of-use rate and the rebate for the water heater itself?
Method. 10-year value = sign-up credit + yearly payment × 10, for one water heater, undiscounted, assuming today’s rates continue. Where a program publishes a range, we show it. Pay per kW-year divides a program’s yearly pay by the average peak reduction measured in that program’s evaluation (0.20 kW for WatterSaver). These are illustrative estimates, not earnings predictions; many programs require minimum connectivity or participation, and some are pilots.
Program terms were collected in September 2026 from utility, program administrator, and regulatory sources. The SMUD figures come from a 2019 program description and may have changed. Programs change often; confirm current terms with your utility before enrolling.
Check your rate before you shift.
Daily load shifting pays off most on a time-of-use rate. See what your utility charges, and what a heat pump costs to run where you live.