WattCost

Data through April 2026

Running cost · Water Heaters (Electric) · ENERGY STAR certified

Carnot Labs, Inc. N51

Heating a typical household's hot water, the Carnot Labs, Inc. N51 is certified at 1,404 kWh a year — about $264 at the U.S. average electricity rate, or $22.03 a month. It sits near the bottom of the certified table — using 30% more than the median electric water heater (rank 536 of 566) — so the state you live in matters more than usual. Where you live moves the bill from $173 a year in North Dakota to $655 in Hawaii.

Estimated annual running cost · U.S. average rate 18.8¢/kWh

$264/yr

$121 · cheapest certified water heaters (electric)$328 · priciest
Per month
$22.03
Per day
72¢
Certified use
1,404 kWh/yr
Type
Hybrid/Electric Heat Pump
Heat pump type
240 Volt Integrated HPWH
Storage volume
47 gal
First-hour rating
75 gal
UEF
3.53
643 kWh1,741 kWh
Where the Carnot Labs, Inc. N51 (▮) sits among all 566 certified water heaters (electric), by annual kWh

What it costs in every state

Carnot Labs, Inc. N51: 1,404 kWh/yr × each state's average residential rate (EIA)
StateRate ¢/kWhThis model $/yrRelative cost
Alabama17.4¢$244
Alaska27.4¢$384
Arizona15.5¢$217
Arkansas14.2¢$199
California35.3¢$495
Colorado16.5¢$232
Connecticut32.2¢$453
Delaware18.8¢$264
District of Columbia25.4¢$357
Florida15.4¢$216
Georgia15.4¢$216
Hawaiipriciest46.6¢$655
Idaho12.7¢$178
Illinois20.5¢$287
Indiana17.9¢$251
Iowa13.9¢$195
Kansas15.8¢$222
Kentucky15.0¢$211
Louisiana14.4¢$203
Maine28.4¢$399
Maryland22.1¢$310
Massachusetts29.4¢$413
Michigan21.4¢$300
Minnesota16.4¢$230
Mississippi16.8¢$235
Missouri14.0¢$197
Montana13.9¢$195
Nebraska13.3¢$186
Nevada14.3¢$201
New Hampshire27.2¢$382
New Jersey23.5¢$330
New Mexico15.2¢$213
New York29.4¢$413
North Carolina16.3¢$228
North Dakotacheapest12.3¢$173
Ohio19.5¢$274
Oklahoma13.3¢$187
Oregon15.8¢$222
Pennsylvania21.5¢$301
Rhode Island28.3¢$397
South Carolina17.1¢$240
South Dakota14.5¢$204
Tennessee14.9¢$210
Texas17.0¢$239
Utah13.3¢$187
Vermont24.6¢$345
Virginia17.4¢$244
Washington14.4¢$202
West Virginia16.1¢$225
Wisconsin19.2¢$270
Wyoming14.7¢$206

Certified models closest in efficiency

electric water heaters within reach of 1,404 kWh/yr
ModelkWh/yr$/yr (US avg)
Friedrich PROH80 T0 FD120-M1,403$264
Friedrich PROH80 T0 FD120-MSO1,403$264
Rheem PROPH80 T0 RH120-M1,403$264
Rheem PROPH80 T0 RH120-MSO1,403$264
Rheem XE80T10HM00U01,403$264
Rheem XE80T10HMS00U01,403$264

Run your own numbers

Your rate, your numbers

Per day
72¢
Per month
$22.03
Per year
$264

1,404 kWh/yr × 18.8¢/kWh = $264/yr

Prefilled with this model's certified 1,404 kWh/yr — adjust if your usage differs from the DOE test basis. The certified annual kWh comes from the DOE Uniform Energy Factor test, which simulates a typical household's daily hot-water draw pattern. Only electric models (including heat-pump units) are listed — gas models burn gas, not kWh.

Questions, answered with the data

How much electricity does the Carnot Labs, Inc. N51 use?
ENERGY STAR certifies the Carnot Labs, Inc. N51 at 1,404 kWh per year. The certified annual kWh comes from the DOE Uniform Energy Factor test, which simulates a typical household's daily hot-water draw pattern. Only electric models (including heat-pump units) are listed — gas models burn gas, not kWh.
How much does the Carnot Labs, Inc. N51 cost to run per month?
About $22.03 a month at the U.S. average residential rate (18.8¢/kWh) — 72¢ a day, or $264 a year. Your state's rate moves this up or down; see the table above.
Is the Carnot Labs, Inc. N51 energy efficient?
It uses 30% more electricity than the median certified electric water heater, which puts it among the least efficient certified models.
What does the Carnot Labs, Inc. N51 cost to run in the cheapest vs. priciest state?
At current residential rates it costs about $173 a year in North Dakota (12.3¢/kWh) and $655 in Hawaii (46.6¢/kWh).

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