Solar + EV integration

V2H battery replacement value calculator

V2H equipment and a dedicated home battery can both get you to the same backup capacity, often at different prices. Add your target capacity and both equipment costs to see which gets you there for less.

Your backup capacity target and costs

1 Project details Optional
2 Target backup capacity
How much stored energy you want available for an outage or peak shaving.
3 Dedicated home battery option
Typical installed cost for residential battery systems runs $700 to $1,100 per kWh.
Permitting, electrical work, and labor not captured in the per-kWh figure.
Confirm current rate on irs.gov.
4 V2H equipment option
Bidirectional charger and home integration hardware.

How it works

Weigh the rest of your backup options

Step 1

Decide your real backup capacity need

Think in terms of essential loads over your typical outage length, not your full home's peak demand. Most backup needs land between 10 and 30 kWh for critical circuits.

Step 2

Get real quotes for both options

Home battery and V2H pricing both vary significantly by brand and region. Two or three quotes for each option give a much more accurate comparison than list prices alone.

Step 3

Weigh availability against cost

A cheaper V2H solution only helps if the car is actually home and charged when an outage hits. Check the V2H payback calculator for the full ongoing value picture beyond just the equipment cost comparison.

Understanding V2H as a battery alternative

Why V2H can provide so much backup capacity so cheaply

An EV battery is already paid for as part of the vehicle purchase, so V2H equipment cost only needs to cover the hardware that lets your home tap into that existing capacity, not the battery cells themselves. A dedicated home battery, by contrast, is purchased purely for backup and storage purposes, so its full cost, cell capacity included, falls entirely on the backup power budget.

The comparison gets better for V2H as capacity needs grow

Because V2H equipment cost is largely fixed regardless of how much of the EV's battery you actually tap into, the effective cost per kWh of backup capacity drops sharply as your target need increases. A household wanting just 10 kWh of backup, per the whole home backup sizing calculator, sees a much closer cost comparison between the two options than one wanting 40 kWh, where V2H's fixed-cost advantage becomes dramatic.

Availability is the real tradeoff, not just cost

A dedicated home battery sits in your garage or utility closet and is always available the moment power goes out, regardless of whether anyone is home or what the car is doing. V2H only works if the vehicle is physically present, plugged in, and has enough charge reserved for backup use, which means a car away on a road trip during an outage provides zero backup value no matter how good the V2H equipment is.

Many households find a hybrid approach works best

Pairing a smaller dedicated home battery, sized for guaranteed critical-circuit backup, with V2H for extended outages when the car happens to be available combines the reliability of always-on storage with the low incremental cost of tapping a large EV battery for bigger backup needs. This hybrid approach is increasingly common among installers designing whole-home resilience systems.

Following up on this result

If V2H comes out ahead on cost, check the V2H payback calculator for the ongoing value from outages and peak shaving combined. If a dedicated battery still makes sense for guaranteed availability, the battery triple sizing calculator helps size storage alongside solar and EV needs together. Here's a related resource: the battery second life value estimator.

Questions

Frequently asked

Often, yes, especially for larger backup capacity needs. Getting 20 kWh of backup capacity through V2H equipment can cost thousands less than buying a dedicated 20 kWh home battery, since V2H equipment cost stays fixed regardless of how much of the EV's battery capacity you actually use.

Because V2H equipment cost doesn't scale with battery size, while dedicated home battery cost scales directly with capacity purchased. The implied cost per kWh of backup through V2H drops significantly as you tap into more of the EV's available capacity, while home battery cost per kWh stays roughly constant.

Not necessarily. A home battery is always available for backup regardless of whether the car is home or charged, while V2H only works when the vehicle is plugged in and has sufficient charge reserved. Some households use both, a smaller home battery for guaranteed always-on backup and V2H for extended outages when the car happens to be available.

Most households reserve a portion of the battery for driving needs and don't count the full rated capacity as available backup. A common approach is subtracting your typical daily driving reserve and any manufacturer-recommended minimum charge level from the total battery size.

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