Your EV as a Battery Backup

In the next part in our series on power outages and home energy usage, we look at electric vehicles.

In the next part of our series on power outages and home energy usage, we look at electric vehicles.

We’ve been asked, not surprisingly, whether a homeowner’s electric vehicle (EV) could be used to power their passive home in a power outage. The short answer: it depends on the vehicle (and your budget).

EVs are still evolving

In the early days of EVs, this just wasn’t an option. They weren’t designed with bidirectional flow in mind, meaning it wouldn’t be possible to pull energy back out of the vehicle’s battery and into the house.

As EVs have evolved, another common problem has been the simple lack of plugs. Without the appropriate plugs, it’s just not possible to make the required connection.

In the original VW eGolf, the only option would have been using the 12 volt cigarette plug with an adapter, and you couldn’t draw much power that way.

The Nissan Leaf has a 120 volt plug, but is limited to 15 amps. Running a cable from this particular vehicle it would be possible to power a small heater or small cooktop unit, but not much else.

The appeal of making use of an EV’s battery storage is obvious: it makes use of a power source that typically sits unused for very long periods of time, and it’s a super quiet alternative to a gas generator.

That being said, there are a lot of interconnecting considerations when it comes to charging an electric vehicle versus drawing power to run your home’s many electrically dependent systems and appliances.

The EV as power plant

The one vehicle currently on the market able to truly handle the demands of shared vehicle / home power is the F150 Lightning, the electric version of Ford’s popular pickup.

This vehicle takes the steps necessary beyond simple bidirectional charging and comes equipped with a panopoly of plugs, and the “extras” (which cost more, of course) required for complete integration: the 19.2 kW Ford Charge Station Pro and the Home Integration system (as well as the services of an electrician, of course).

This excellent article on Car & Driver makes the case for the F150 Lightning over the Tesla Powerwall, but do be sure to check current pricing right on Ford’s website or with your local dealer.

“To appreciate how much electrical power the Lightning can provide, consider that even the standard-range version has a usable battery capacity of 98.0 kilowatt-hours, more than seven Tesla Powerwalls—a well-regarded home battery, The Powerwalls cost $10,500 each, while a base Lightning costs only $41,769—43% less than seven Tesla batteries—plus you get a truck for free.”

Car & Driver, Can Your EV Power Your House? (Pricing comparison is from spring 2022)

Power needs of a passive home

As we’ve discussed in many other posts, the energy needs of your passive home will be dramatically smaller than a home built to past or current code.

The claim that the F150 Lightning could power your home for three days stretches much further for a fully passive home.

We’ve assessed that it could probably power our model home for upwards of two weeks (1,600 sq ft bungalow), on a single charge.

Limiting factors

There are, as always, some limiting factors to bear in mind. The heat pump used in our homes requires 30 amps, which would be too much in a cold weather power outage scenario.

Instead, a 15-amp portable electric heater would be deployed, and we have a great recommendation for this: the Senville 900W/1500W Tower Ceramic Heater with Remote, Digital Thermostat, Overheat Protection is an excellent choice that can comfortably heat a 1,500 or 1,600 sq ft passive home.

Planning your passive home

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If you’re planning a passive home as part of being ready for the future, check out our 50+ passive house plans, learn about our passive house webinar, or just reach out to discuss your project. We ship our passive house plans and kits across North America. We’d love to hear from you.

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