Solar plus Heat Pump Water Heater – Smart Solar

(An update from our June 2013 blog)
Solar is becoming more widely known as a practical way to save money on your electric bill, by making some of the power yourself rather than buying it all from the electric company. A lesser known way to bring your utility bills down even lower is to also install a heat pump water heater, also known as a high efficiency water heater, or Energy Star water heater.

solar water heating with heat pumps

Solar electric systems combined with heat pumps for water heating greatly reduce your annual costs.

Traditional Water Heaters Big Consumers of Energy & Money

A traditional electric water heater is generally the second largest user of electricity in a home, and can account for as much as a quarter of a household’s electricity use. A hybrid heat pump water heater can reduce that electricity use from around 13kWh (kilowatt hours) a day to 5kWh a day. Thats an annual savings of 3,000kWh.  A heat pump water heater works by taking the heat from the air, and putting it into the water in the tank. A

hybrid model also has a backup electric heating element to ensure there is always plenty of hot water available. They work the same as the heat pumps used to heat your house, but with a smaller pump that is generally built right on top of the water heater.

Solar Water Heating isn’t Solar with Heating Heat Pumps 

So you may be asking yourself, what does this have to do with solar? Am I talking about solar water heating? No. This is electric water heating, by using the electricity generated by your solar electric system.  In most locations, 1,000 watts of solar electric panels could provide enough electricity to power the heat pump water heater, while in comparison a traditional electric water heater would need around 4,000 watts of solar power. This is a less expensive and less complicated solution than solar water heating. What this means is if you are installing a grid tie solar electric in your house, you could get the same reduction in your electric bill by replacing your electric water heater with a heat pump water heater, with 3,000 watts less solar. Or, install the same amount of solar, and see it offset an even higher percentage of your smaller electric bill.

Swap Out that Oil Water Heater

Many people who currently heat their water with oil can see a reduced oil bill, and only need to add 1,000 watts of solar to their planned solar system to offset the slight increase in electric use seen by switching from oil water heating to electric. This is very popular in the Northeast where oil heat is common. Now you never have to hear your oil furnace kicking on every day in the summer just to heat your water. In the winter, the heat in the air surrounding the furnace can get pulled right into your water – even heat from a cool basement. Think of using solar with a heat pump for water as free “solar fuel oil” – one whose price will never change above that magical amount of $0.

Heat Pumps are also Basement Dehumidifiers

Heat Pump Water Heater

A heat pump water heater from Stiebel uses 25% the energy of a normal electric water heater.

Another advantage of the heat pump water heater is that while it is taking the heat out of the air, it is also removing the humidity from the air. This can be very beneficial in homes where the water heater is installed in the basement. Keeping the basement cool and dry in the summer can eliminate the need for a dehumidifier in the basement, even further reducing your electric bill by another 1,000kWh a year. Homes in warm climates without a basement can install the heat pump water heater in their garage, providing the same benefits there.  

Financial Incentives Available in Many States

The energy savings of a heat pump water heater is so great that many states have created cash incentives to swap out your old electric water heater. For instance, in Massachusetts, National Grid customers can get a $750 rebate by having a heat pump water heater professionally installed. Go to to DSIRE and go to your state to see if there is an Energy Efficiency rebate program available in your area. Note that this is different from the solar water heating rebates, this is for high efficiency, Energy Star, or heat pump water heaters.

Partial List of Rebates Available for Heat Pumps

State Utility Incentive
California Pacific Power $600 rebate
California  PG&E $500 rebate
Georgia  Georgia Power $250 rebate
Hawaii  Hawaii Energy $300 rebate
Massachusetts  National Grid $750 rebate
Maine  efficiency Maine $500 rebate

For more details on heat pump water heaters, see the brochure for the Stiebel Eltron Accelera 300.

About Author

Amy Beaudet
Amy Beaudet was in the solar industry at the altE Store from 2007 until her untimely passing in 2021. She was a sales rep, instructor, and an all-around solar evangelist, sharing her passion for solar around the world. When whe wasn't at work, she enjoyed sailing and skiing - but odds were good she was still talking about solar on the boat or on the slopes. See more of Amy Beaudet's blog posts.


  1. Solar Installation Las Vegas

    I really like the information provided in this article. thanks for sharing with us

  2. Joseph Corcoran

    We installed a GeoSpring heat pump water heater in our off-grid cabin a few years ago and it works fine (knock on wood!) so far.

    We keep it set to operate in heat pump mode only – as opposed to resistance heat, or a combination of both, and set the temperature to 120 degrees.

    It has served us well so far and since we have it located in the crawl space of our cabin, it keeps the humidity down and actually provides a bit of cooling of the cabin floor in the summer. In winter time, the crawl space stays in the 40 – 60 degree F temperature range and the heat pump extracts that heat from the air to heat the water.

    Overall, it appears to be a good fit for our Ouachita Mountain climate in western Arkansas.

  3. leeshin12

    very useful blog. thank you for sharing

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