The Question We Keep Getting
If you've invested in solar and a home battery system, you've made a smart call. Products like the Tesla Powerwall 3, Franklin WH, and EG4 PowerPro have made whole-home backup power more accessible than ever. For homeowners in North Dakota and Minnesota — where a February ice storm or a July thunderstorm can take the grid down for days — backup capability isn't a luxury. It's peace of mind.
But there's a question we hear more and more: "My electric vehicle has a massive battery sitting in the garage. Why can't it help power my house too?"
Fair question. And the honest answer is: it should. It just can't yet — not easily, and not cheaply.
What Your Battery System Already Does Well
Here's something most homeowners don't fully appreciate: the most expensive and complex piece of a home backup system isn't the battery itself. It's the equipment that manages the transition between grid power and backup power — the transfer switching system.
When grid power goes out, something has to automatically disconnect your home from the utility line (to protect lineworkers), switch your loads over to battery power, and manage that transition seamlessly. The Tesla Gateway, Franklin WH's whole-home backup system, and the EG4 PowerPro all include this capability built in. That hardware is sophisticated, code-compliant, and — when set up correctly — nearly invisible. The lights don't even flicker.
The point: the hardest part of home energy backup is already solved. These systems know when the grid goes down, they know how to isolate your home safely, and they know how to manage your solar and battery to keep you running.
So Why Can't Your EV Plug Into That?
Your electric vehicle — whether it's a Ford F-150 Lightning, a Kia EV6, or a Rivian — is essentially a very large battery on wheels. A typical EV carries 60 to 100 kWh of usable energy. A Powerwall 3 holds 13.5 kWh. One fully charged EV stores the equivalent of four to seven home batteries.
Vehicle-to-home (V2H) technology would let that EV battery act as an extension of your home storage — feeding power back through a charger into your electrical system during an outage or during peak rate hours.
The hardware exists. Several EVs have onboard electronics to push power back out through the charge port. Bidirectional chargers are on the market. Your transfer switch is already in place.
The problem: none of these pieces were designed to talk to each other.
Each manufacturer built their own ecosystem with their own communication protocols. Tesla's Powerwall and Gateway only fully understand Tesla vehicles — and even that integration has been delayed. Ford's backup system works with the F-150 Lightning but doesn't recognize a GM vehicle. EG4 and Franklin aren't part of any automaker's V2H program.
Adding V2H to an existing storage system from a different brand often means installing a second transfer switch, additional control hardware, and custom wiring to bridge systems that weren't designed to coordinate — all at significant added cost for something that should just work.
What's Changing
The industry knows this is broken, and standards are in progress.
ISO 15118-20 is the key standard — it defines a common communication language between EVs and chargers for bidirectional power flow. Published in 2022, it's starting to appear in new vehicles and charging equipment. The EU has mandated that new V2G-capable public chargers support it by 2026. North America is moving in the same direction, and the first vehicles and chargers built around this standard are reaching the market now.
Alongside that, work is underway to standardize how chargers communicate with home energy management systems — the piece that would finally let your EV, battery, solar, and transfer switch operate as a single coordinated system rather than separate islands.
We're probably two to three years away from broad availability at a reasonable price point. But the direction is clear.
What This Means For You Right Now
If you're shopping for a home battery system today, the technology you're investing in — the transfer switch, the inverter, the battery management — will still be relevant when V2H interoperability arrives. These aren't throwaway products.
What we'd encourage: think about the full picture before you buy. Not just how many kilowatt-hours of storage you want today, but what kind of expandability makes sense for your situation, which products are most likely to be part of an open ecosystem as standards develop, and whether V2H matters enough to influence which EV you drive.
These are exactly the conversations we have with customers every day. If you're thinking about solar and storage — or wondering how a system you already have fits into what's coming — we'd love to talk.
Contact Holsen Solar & Electrical to schedule a conversation →