How vehicle-to-home works
A normal charger only sends power into the car. A bidirectional charger can also draw power out and feed it to the house through equipment that isolates your home from the grid during an outage. Your panels, the car and, optionally, a stationary battery then work as one backup system.
Our setup uses SigEnergy’s bidirectional DC charger, which pairs with SigEnergy’s battery and inverter platform. Adding the bidirectional charger to a SigEnergy battery system runs about $3,500; a whole-home bidirectional backup system starts from about $19,000.
Which cars work
This is the part to be careful about. Only some vehicles support exporting power through a DC bidirectional charger, and support depends on the manufacturer, model year, charging standard and software. A car that advertises “power export” for tools or camping may not support whole-home backup with a given charger.
We check your specific vehicle against the charger maker’s current compatibility list before we quote. If your car isn’t supported, we’ll tell you, and a stationary battery may be the better answer for now.
How long an EV can run a house
A mid-size EV battery can run essential loads for several days, and a large truck battery longer, while still leaving range to drive. Most owners set a floor so the car keeps enough charge to leave if needed — in a wildfire evacuation, that matters.
Our EV-as-backup calculator turns your vehicle’s battery size and your essential loads into days of backup.
What it doesn’t do yet
Using an EV to lower your bill every evening (vehicle-to-grid or routine peak shifting) raises utility interconnection and warranty questions that are still being worked out. Check your vehicle warranty’s terms on bidirectional use. For daily time-of-use savings, a stationary battery is the more predictable tool today; the EV shines as a very large backup reserve.
FAQ
Questions we hear
Can any EV power my house?
No. Only certain vehicles support bidirectional DC export for home backup, and support varies by model year and software. We verify your exact vehicle with the charger maker’s compatibility list before quoting.
How much does bidirectional EV backup cost?
Our whole-home bidirectional backup systems start from about $19,000. If you already have or are buying a SigEnergy battery system, the bidirectional charger adds about $3,500.
Will using my EV for backup hurt its battery?
Occasional outage backup is a light duty cycle compared with driving. Daily cycling is a different question. Check your manufacturer’s warranty language on bidirectional use.
What if the car is gone when the power goes out?
That’s the practical weakness of EV-only backup. If someone commutes daily, pairing the charger with a stationary battery keeps the essentials running when the car isn’t home.
Do I need solar for EV home backup?
No, but solar lets you recharge the car during a multi-day outage instead of watching its range drop. Most of our bidirectional systems are paired with panels.