Claire’s position on this, delivered over dinner in January 2024, was unambiguous: “We are not ripping out a working furnace.”
She had a point. Our gas furnace was four years old. The gas water heater was three. Replacing functioning appliances purely for ideological reasons is not how either of us thinks about money. But the question I kept returning to was different: what happens when these appliances reach end of life? What does the full electric replacement path actually cost — and does our solar system already sized for it?
Spoiler: it didn’t. My 9.6kW system was sized for our 2022 electricity consumption. Adding a heat pump, heat pump water heater, and induction range would add roughly 3,200–4,800 kWh per year to our load. That’s a meaningful miss.
Here’s what the full electrification path looks like and how solar connects to it.
The Four Appliances That Define Whole-Home Electrification
Gas furnace → Air-source heat pump: The centerpiece of whole-home electrification. A modern heat pump (Mitsubishi, Bosch, Carrier, Lennox) moves heat rather than generating it, achieving 250–400% efficiency at moderate temperatures. In Austin’s climate, a heat pump handles both heating and cooling — replacing both the furnace and AC in one unit.
Cost: $5,000–$12,000 installed, depending on system size and whether ductwork modifications are needed. Annual electricity increase: 1,800–3,200 kWh for a typical Texas home (replacing gas heat; cooling load stays similar since you likely had central AC already). Federal credit: 30% ITC for heat pumps under the Inflation Reduction Act — up to $2,000 per year.
Gas water heater → Heat pump water heater: The second-highest impact appliance switch. A heat pump water heater (Rheem ProTerra, AO Smith Voltex) uses 60–70% less electricity than a conventional electric resistance water heater. It’s not just “electric” — it’s efficient electric.
Cost: $1,200–$2,000 installed. Annual electricity increase: 800–1,200 kWh replacing a gas water heater. Federal credit: 30% ITC up to $600 per year.
Gas range → Induction range: The most visible switch but the smallest energy impact. Induction cooking is faster and more efficient than gas, and eliminates indoor combustion pollutants. The cooking load is a small fraction of total home electricity.
Cost: $800–$2,500 for the range itself; may require a 240V circuit installation ($200–$500). Annual electricity increase: 200–400 kWh.
Gas dryer → Electric heat pump dryer: Heat pump dryers (LG, Miele, Electrolux) use 40–50% less energy than conventional electric dryers. Less dramatic than the heating appliances but part of a complete gas elimination.
Cost: $800–$1,500. Annual electricity increase: 100–200 kWh (replacing gas; heat pump dryers actually use less energy than gas dryers in most cases).
The Solar Resizing Question
The total additional load from full electrification: approximately 3,000–5,000 kWh per year for a typical home. Adding an EV simultaneously (as we did) adds another 2,500–4,000 kWh.
My 9.6kW system produces about 14,800 kWh per year in Austin. My pre-electrification consumption was 9,148 kWh. Adding full electrification and an EV brings consumption to roughly 14,600–17,500 kWh — right at or above my current system’s production.
The right sequence: plan the electrification before sizing the solar. If you know you’re going to add a heat pump and an EV in the next 3–5 years, size your solar system for that future load now. Expanding a system later (adding panels) is possible but costs more per watt than including them in the original installation.
The Federal Incentive Stack for Full Electrification
The Inflation Reduction Act created a layered incentive structure for home electrification that, combined with the solar ITC, makes the economics meaningfully better:
- Solar system: 30% ITC on full installed cost
- Battery storage: 30% ITC on battery cost
- Heat pump HVAC: 30% credit up to $2,000/year
- Heat pump water heater: 30% credit up to $600/year
- Electric panel upgrade (if needed to support new loads): 30% credit up to $600/year
- Heat pump dryer: 30% credit up to $500/year
The annual cap on the non-solar credits ($3,200/year combined) means phasing purchases across multiple tax years maximizes the benefit. Don’t buy the heat pump and water heater in the same year you install solar if you’re near the cap limits.
The practical case for whole-home electrification is strongest when you’re replacing appliances that have already reached end of life. Ripping out a working furnace like Claire suggested I wasn’t going to do — she was right. Replacing a 15-year-old furnace with a heat pump instead of another gas furnace is a different calculation entirely.
— Allen
