Score breakdown: 82/100
RatingPlate Score. Based on EIA energy prices, ENERGY STAR data, state rebate programs, and permit research. Not a government rating or purchasing recommendation. FAQ
Hawaii electricity is 145% above the national average. Here's what that means for heat pump operating costs.
Running cost in Hawaii
At Hawaii's 44.3¢/kWh electricity rate, the most efficient heat pump water heater saves an estimated $1624 per year compared to a standard electric tank.
Hawaii electricity
44.3¢
per kWh (EIA, 12-month avg. through Aug 2026)
Best HP annual cost
$368
A. O. Smith HPTS-50-2
Electric resistance
$1992
~4,500 kWh/yr baseline
Warmer inlet water (72°F annual average) means heat pump efficiency may exceed rated UEF in Hawaii. Less temperature rise needed, lower energy consumption.
Heat pump vs gas tank in Hawaii
At Hawaii prices (44.3¢/kWh electricity, $5.86/therm gas), a heat pump costs about $635 less per year to run than a standard gas tank, on the same DOE rated hot water load. See replacing a gas water heater in 2026 and all 50 states compared.
Heat pump
$379/yr
855 kWh/yr (median 50-gal)
Gas tank
$1014/yr
173 therms/yr (UEF 0.64)
Difference
$635/yr
heat pump cheaper
Both use the DOE medium draw test load (55 gallons a day). Gas price: EIA, 12-month avg. through Aug 2026. Replacing gas with a heat pump also means adding a 240V circuit (or choosing a 120V model) and a condensate drain, and the federal HEAR rebate no longer covers gas replacements.
Why Hawaii changes the call
01Energy costHawaii electricity is 145% above the national average. That directly affects how much a heat pump saves compared to a standard electric tank.
02Climate impactIncoming water averages 72°F annually and drops to about 70°F in winter. Colder water means the heat pump works harder and real efficiency is slightly lower than rated.
03Available incentivesState and utility rebates can significantly change the payback period. Check what's currently available before finalizing your decision.
Rebates in Hawaii
Hawaii has 1 rebate program as of November 2026.
The federal $2,000 tax credit (IRA Section 25C) expired December 31, 2025. State and utility rebates listed below may still be available. Verify current status at the links provided.
Hawaii Energy Heat Pump Water Heater Rebate
$500 (40-54 gal) / $700 (55-82 gal)
Who: Hawaii Energy (ratepayer-funded, administered by Leidos)
Eligibility: ENERGY STAR certified. 40-82 gallon tank. Instant in-store rebate at participating retailers. Available to residential electric utility ratepayers on Hawaii Island, Lanai, Maui, Molokai, and Oahu only (not Kauai). Program year runs through June 30, 2027, while funding lasts.
https://hawaiienergy.com/for-homes/rebates/water-heating/
IRA HEAR Rebate (Point-of-Sale)
Not yet available in Hawaii as of November 2026. Up to $1,750 for income-qualified households when available. Under federal guidance effective May 29, 2026, this rebate covers replacing an existing electric water heater (or new construction). Replacing a gas, propane, or oil water heater no longer qualifies.
As of October 2026, Hawaii has not launched its federal HEAR (now called HEEHR) or HOMES rebate programs. The Hawaii State Energy Office says launch is pending U.S. Department of Energy approval and the programs will be available to residents in early 2027.
Install requirements in Hawaii
Code basis: Based on UPC with state amendments
Seismic strapping
Required due to seismic zone classification.
Solar water heating
Hawaii requires solar water heating systems on new single-family residential construction (Act 204, effective 2010), with exemptions available if solar is not feasible.
Electrical
Dedicated 240V, 30A circuit (most models). Some newer 120V plug-in models exist but most residential units require 240V. Check the unit's nameplate for exact requirements.
Condensate drain
Heat pump water heaters produce condensate during operation. A condensate drain line to an approved location (floor drain, condensate pump, or exterior) is required.
Air space
Approximately 700 cubic feet of surrounding air (roughly a 10x10x7-foot room). The heat pump extracts heat from surrounding air. Insufficient air volume reduces efficiency and can cause the unit to underperform. Some manufacturers allow ducting to supplement air supply in smaller spaces.
Noise
Heat pump water heaters produce operational noise similar to a window AC unit (45-55 dB). Consider placement away from bedrooms.
Best fits for Hawaii
A smaller set of representative fits using Hawaii's 44.3¢/kWh rate. Curated to show different trade-offs instead of listing every published model on every state page. See the full heat pump lineup.
Prefer to buy online? The 46-gallon Rinnai REHP50BM is a heat pump available on Amazon.
Common questions: Hawaii
Is a heat pump water heater worth it in Hawaii?
Yes. Hawaii scores A on RatingPlate's analysis, with estimated savings of $1624 per year compared to a standard electric tank. Payback on the higher upfront cost is roughly 1.5 years before rebates.
What rebates are available for heat pump water heaters in Hawaii?
Hawaii has 1 rebate program. The IRA HEAR program has not launched in Hawaii yet. Verify amounts and eligibility at the links in the rebates section above.
How much does a heat pump water heater cost to run in Hawaii?
At Hawaii's electricity rate of 44.3 cents per kWh, the most efficient heat pump water heater costs about $368/yr to run. A standard electric tank costs about $1992 per year.
Do I need a permit for a heat pump water heater in Hawaii?
Hawaii has 2 state-specific requirements: Seismic strapping, Solar water heating. Most jurisdictions also require a standard plumbing or mechanical permit. Check with your local building department.
What is the payback period for a heat pump water heater in Hawaii?
Without rebates, the payback period in Hawaii is approximately 1.5 years based on $1624 in annual savings versus a standard electric tank. With available rebates, payback could be significantly shorter.
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Sources
Electricity and natural gas rates: U.S. Energy Information Administration, residential sector (EIA, 12-month avg. through Aug 2026).
Rebate data compiled from state energy offices, utility program pages, DSIRE, and ENERGY STAR. Rebate amounts and eligibility change frequently. Verify at listed program URLs.
Inlet water temperatures estimated from NOAA climate normals using the Burch-Christensen mains water temperature model (NREL).
Model specifications from ENERGY STAR certified product data and manufacturer spec sheets.
Page updated November 1, 2026. Data freshness varies by source.
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