Our Kirkland, WA home is 100% electric since April, 2025, after we replaced our gas furnace and gas water heater with heat pumps. Gas line capped; gas service cancelled. On our roof, south-facing solar panels have average 9,300 kWh/yr of clean energy since 2020. We expect our PSE bill to be only the connection fee, $7.95/month–ad infinitum. How so? Read on.

In November, 2020, we installed 24 solar panels totaling 8.2 Kilowatts (kW) on our south-facing roof, more kW than met our then need. We had moved to our Juanita neighborhood in 2018 into an all gas home—gas furnace, gas water heater, gas dryer, gas stove. After the solar installation, we expected to phase these appliances out as they aged. Immediately, I wanted to replace the old gas water heater—the second-biggest energy user—but the cramped space required re-piping the furnace gas line as well. So we didn’t act; instead, we kept our fingers crossed it wouldn’t fail. In late 2022, the 30-year-old gas stove died. We replaced it with induction.¹

In 2024, Energy Smart Eastside (Bellevue, Kirkland, Redmond, Mercer Island, Sammamish and Issaquah) began offering $6000 to replace a gas furnace with a heat pump, which runs solely on electricity.² That incentive derives from the 2021 Washington State Climate Commitment Act, so it’s likely to be available for some time. Additionally, a federal tax credit of $2000 is available thru 2025, and Puget Sound Energy has a $600 rebate.

Heat pumps for space heating have a reversing valve that allows them to cool as well as heat, a good we wanted due to increasingly hot summers. We decided to act. For our situation, it made sense to replace our remaining gas appliances all at once. We had three Energy Smart Eastside-approved installers bid on replacing both the gas furnace and old water heater together. Installation took less than a day, on April 4, about a month after we awarded the work. We donated the gas furnace and gas dryer, which had some life left,³ to Habitat for Humanity. The gas water heater was carted off for scrap.

Now August, it’s early days, but we’re impressed with the new kit. A big concern was neighbors hearing the heat pump outdoor unit, but when asked they’ve said no. The indoor air blower is quieter than the old gas furnace as well. The heat pump water heater hums when operating in the garage, but we can’t hear it inside the house. Since the summer garage air is warm, the water heater is efficiently channeling that warmth into hot water, for now with little energy use. I am a bit concerned come winter, though, when efficiency will drop. The water heater is a hybrid; when garage temperature dips below 37F, water heating switches from heat pump to electric element(s).

Concerning winter space heating, the new heat pump is Cold Climate—no inefficient⁴ back-up resistant heat. These modern-day heat pumps instead use a variable-speed compressor and fan drives to increase capacity as the temperature drops. Heat pump technology has come a long way. As such, the cold outdoors won’t be a comfort worry, although efficiency does decline at low temperatures. I’ll report on that next April.

So far, through the end of July, I can say the AC load on our electric use is almost negligible. Importantly, our summertime routine has not changed from our days of no AC. Our home has excellent north-south ventilation through windows and doors, and a ventable skylight. We take full advantage. In general, we first check the forecast. If that’s above 78-80F, we open windows in the evening and more so in the early morning, and occasionally engage a fan to further cool the interior. By late afternoon on hot days, when the indoor thermostat reaches about 76F, the AC is turned on manually, thermostat set at 75F.

Reviewing the April to July outdoor temperature data and our call for AC, there were days (6) when the max outdoor temperature reached 85F or more; these are the only days the AC operated. On the hottest day, July 16, outdoor temperatures soared to 93F and we ran the heat pump from about 3pm-8pm.⁵ The heat pump used no more than 7 kWh that day.⁶ I would put our total kWh expenditure for AC, April thru July, at 30-35 kWh. At $.15/kWh that’s about $5.

Winter will be a bigger challenge. But, some good news. As many of you know, Washington’s current law regarding solar requires “net metering”: the electric utility (PSE) records solar production out to the grid, and of course, electricity delivered into the home. For us, about seven months of the year we export more than we import. We expect to “bank” enough summer kilowatt-hours to get us through the winter and almost to April. Then—with the lengthening days—our solar production will again exceed the needs of our home.

More about our 2020 solar installation can be found here: https://garyluhm.net/western-washington-rooftop-solar/

Note: Sad to say, many people in this country have been conned into thinking solar isn’t an option, only (government-subsidized) dirty energy is. There are many ways in which solar works (it started years ago with the space program and consumer items like pocket calculators). In many parts of the USA—and especially the world—it has become the cheapest energy source, producing clean, highest-quality energy: electricity. Solar is also the quickest to install. USA is a brittle country to rely on fossil fuels. Solar energy is energy security. On USA’s current path, this will not end well. I’m happy to say in closing, though, there is a path forward. The move to electrify buildings, machinery, much of transportation, and more—fueled in part by solar—over time will factor hugely toward (pick your concern) real national security, energy independence and/or a way forward in dealing with the climate crisis.

I wrote a follow-up regarding all-electric homes using less energy. In our case, 56% less: https://garyluhm.net/all-electric-homes-use-less-energy/

Gary

Footnotes:

¹Induction stoves work with cast iron pans, or steel cookware that contains iron. In use, an alternating current sets up a magnetic field, which collapses to creates current that converts to heat directly in the cookware. These stovetops are extremely efficient, quicker to heat than gas and fantastic for control with instant on-off and everything in between. The glass surface doesn’t get very hot, so it’s also safer and easy to clean.

²Over time, as electricity generation comes more and more from renewables, the carbon footprint of electrically-run equipment decreases.

³The furnace and gas dryer were seven years old, in good shape–you could say lightly used–with quite a bit of life left. Normally, it makes economic sense to replace appliances only at or near end of life. Our local climate, however, is not the same as a few decades ago. Summers that were tolerable without AC are increasingly not so. Scary that our changing climate isn’t a “new normal”, as some say. We’re in transition toward further warming, with probable catastrophic tipping points.

⁴Technically, resistant heaters aren’t really inefficient. Almost all the electricity (98% or so) converted to heat is delivered, with space heating, directly to the air. The heat pump, however, typically operates averaging 300% efficiency, or more, because it MOVES heat using a refrigeration cycle (and does not, BTW, violate the laws of thermodynamics!).

⁵For PSE Flex events, which will occur when high or low temperatures stress the grid, we will adjust our strategy. For example, for a summer event, we would likely cool our home beforehand and shut off air conditioning and other appliances and then coast through the event. Lowering use during peak demand saves everybody’s bottom line. PSE offers modest financial rewards for cutting back during Flex events, see https://www.pse.com/en/rebates/PSE-flex/flex-rewards/

⁶I calculated this by eye-balling the area under the curve (kW x h = kWh) from the 3-8 pm spike in the solar app’s day graph (left), which tracks solar production and utility input in 15 minute intervals.