As EVs go mainstream over the next few years, many customers will be asking the same question: Can I use my EV as a battery backup at home? Many EVs work with fast chargers installed in the garage, and these chargers can double as house batteries. So, can you plug your house into your car just like you plug your car into your house? Here is how EV backup power works for power outages.

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Using your EV to power your home

Electric car batteries can hold 60 kWh of energy, which could provide backup power to an average U.S. household for about two days. That means that for a short average power outage, your EV could be a great backup power option. But there are problems. What if you use up your battery and the power doesn’t come back after two days? You would be stranded at home with no power and no transportation. Just as you might keep gas cans for backup generators on hand, you should have a backup power option even for your backup.

Related: How to make your home energy more efficient for a tax rebate

Home battery and electric car as power backup

If you get an EV and are planning to install a fast-charger in your garage or parking spot, make sure to ask questions not only about how quickly the charger can juice up your EV, but how much power it can hold. There are now house batteries that can both charge your EV and your home in a power outage. If you buy an EV that can reverse power back to your house, it’s going to take a lot of energy. Having a house battery might be a better option than draining your car. But if you get both, now you have some options.

Some EVs allow you to plug in your phone, laptop or power tools. Larger pickup trucks can sometimes function as an independent power station on the move, so if you’re thinking about a larger vehicle, definitely check into these options. Many electric pickups have outlets in the bed of the truck or cords that can be used to charge other devices like saws.

What you won’t find is a lot of EVs that are designed to automatically plug into an entire house. If you’ve wrangled with a generator, you know that many smaller power backup generators can’t power a whole house. You have to plug the generator or battery backup into your house’s main power but turn off draining appliances on the circuit, or you have to install a whole house generator, which can be much more expensive. When you buy an EV, similarly, you will much more often find smaller cars that can charge your laptop or maybe power the fridge. This is a perfect solution for smaller households.

Got a big household? Proterra makes electric buses that store 660 kWh of energy, and larger electric trucks for garbage pickup and shipping are also heading into production. If you buy a larger EV, ask about whether it is equipped with V2G, vehicle-to-grid or vehicle-to-home technology so you can power the entire building off the vehicle battery. This should be a very convenient way to help first responders powering up disaster areas and severe power outages in the future, as the electric vehicle bringing first responders to the scene could also serve as a mobile power station — an invaluable thing after a severe tornado, for example, when the local grid is down.

V2G isn’t really a thing yet though, right? Well, Texas actually leads on this trend, believe it or not. In 2018, the Pecan Street Inc. company started integrating the first V2G vehicles in the sprawling state, using a 2019 Nissan LEAF with 40kWh battery in Austin for a pilot project to demonstrate the technology. This program helped the local grid reduce load during ERCOT’s 4CP events.

Also important is to note that the vehicle didn’t experience battery degradation from the daily charging and discharging requested by the utility company, which suggests that EV batteries — even typical small ones found in Nissan LEAF EVs — might be tuned to serve as V2G or V2H purposes. Regulatory approval could slow this process down, but it’s only a matter of time before we realize as a society that switching to sustainable EVs means we’re all driving giant battery packs around and should be able to use them to power all sorts of devices — not just for emergencies but for convenience.

What would it take to power America with EVs?

Maybe this is a ridiculous question, but it is theoretically possible to design a smart grid that pulls from EVs as well as solar installations on homes. Smart Charge America’s Joseph Barletta says that if Texas had 10 million EVs, the state could have met most of the energy shortages during the famous Texas blackouts. Texas currently has 35,000 EVs, but that number will likely expand exponentially in a few years as automakers phase out ICE engine vehicle sales.

And maybe we have been too hard on Texas recently about their fragile grid and out-of-date climate policies. The state is starting to switch over to all electric buses soon. If buses or emergency vehicles could be used for mobile battery backup, this kind of decision to switch to EV buses could have large implications for how municipalities respond to power outages. All we need is more V2G-equipped EVs of all size.

It really comes down to infrastructure to get the world on track to a sustainable future. If we start to think about EVs as part of the infrastructure itself rather than the machines pulling on energy, the possibilities for a resilient smart grid supported by mini grids created by power-producing homes and vehicles open up.

Nissan is making a LEAF-to-home system to support this goal. Proterra buses and Dominion Energy in Virginia are creating city and school buses respectively to create large-scale school bus vehicle-to-grid programs. Some people have suggested that swappable batteries from EV school buses could be repurposed outside of the school year to support local grid capacity. There are so many options for configurations of this type of flexible grid, it’s really quite exciting to think about how much better our grid could be in just a few years with the adoption of V2G-equipped EVs.

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