Question

I have a 7.7 kW south-facing PV system. Would an electric heat pump be the best option to heat and cool my home?

Asked by Chris Di Giacomo
Shirley, NY

My home is 1000 sq ft. I have a 7.7 kW PV system that produces about 40+ kWh a day -- more than double what I use. I currently have no heat because the house was a remodel and the old oil burner, chimney, and plumbing have been removed. Since I have the extra electric from the PV, would it make sense to get electric heat instead of a new oil burner? Gas is not available in my area. I looked into geothermal but it was way out of my budget. I then looked into heat pumps with backup electric coils. A heat pump would also allow me to have central air and get rid of several window ACs. Is a heat pump the best option for my situation?

Answer

Great PV system!

If you decide to go the heat pump route, make sure you find a very experienced installer.

  • The data shows that heat pumps are very efficient; however, they are so often poorly installed that the efficiency is generally reduced by 50% due to several common installation deficiencies.
  • They are also very expensive.

If you have an electric hot water heater, perhaps going combined hydronic heating would be a very efficient choice. The conventional hot water tank would be hooked up to a variable-speed air handler and a forced-air duct system would be installed. Then you can install a conventional Energy Star-rated (14 SEER) 1.5 ton a/c condensor that can also run off your PV.

No matter what, make sure that you have a duct-blaster test to ensure that the ducts are tight. Less than 3% leakage is acceptable.

 

For more information:

Read Rick Goyette's Q&A "Should I go with an air source heat pump or electric radiant floor heat?"

Also, read Florian Speier's Q&A "Can I configure an electric tankless water heater to run a baseboard hot-water heating system?"

Do you have a question about greening your home? GreenHomeGuide invites you to Ask A Pro. Let our network of experienced green building professionals – architects, designers, contractors, electricians, energy experts, landscapers, tile & stone specialists, and more – help you find the right solution.