Short answer: on Dominion Energy's standard plan, a home battery saves you almost nothing. The savings don't come from the battery — they come from switching to the time-of-use plan (Rate 7) and using the battery to dodge the expensive window. Get that part wrong and the math doesn't work.
I run this setup at my own house in Charleston, so this isn't a spreadsheet guess. Here's what my actual bills show — and the catch nobody mentions.
The numbers from one real month
In June, my house used 1,846 kWh. Here's that exact same usage priced two ways:
| Cost | |
|---|---|
| On Rate 7 (time-of-use) + a battery | ~$190 |
| That same 1,846 kWh on Rate 8 (the standard plan) | ~$311 |
That's roughly $120 saved in a single month — for identical usage, on the identical house, just a different rate plan with a battery doing the work. (These are my real electricity charges; your home's number will differ with your usage and habits — that's exactly what the analyzer works out for you.)
Why the standard plan can't save you money
Dominion's standard residential plan (Rate 8) charges roughly the same price per kWh no matter when you use it. A battery that charges and discharges on a flat rate just shuffles the same-priced energy around — there's nothing to arbitrage. You'd pay for the hardware and save pennies.
Rate 7 is what changes the game. It's a time-of-use plan: electricity is cheap most of the day and overnight, and expensive during a short on-peak window. The strategy is simple:
- Charge the battery when power is cheapest (the overnight super-off-peak band).
- Run the house off the battery during the on-peak window — so you buy almost nothing at the expensive rate.
Do that consistently and most of your usage shifts to the cheap bands, while the costly window gets covered by stored energy. That's the ~$120/month. (It's also why switching to Rate 7 without a battery can backfire — see Rate 7 vs Rate 8: which is actually cheaper.)
The catch most people miss: the demand charge
Here's the part that gets glossed over. Rate 7 isn't just expensive energy during the peak — it also has a demand charge, set by your single highest 15-minute interval of on-peak power use all month. It's not an average — and it's not quite all-or-nothing either: that one worst moment sets the charge, and the bigger that spike is, the more it costs.
The practical upshot: your battery has to be sized to cover your peak every day the window applies — one big uncovered spike sets that whole month's charge. That's achievable (my bills prove it), but it's a real requirement, not a footnote. Here's exactly how the Rate 7 demand charge works →
Know your on-peak window — it changes by season
The window you're covering isn't the same year-round:
- Summer (May–September): on-peak is 4–8 p.m.
- Winter (October–April): on-peak shifts to 6–9 a.m.
Today that on-peak window applies weekdays only (major holidays excluded). But here's the important part: Dominion has proposed changes for July 1, 2026 that drop the weekday limit — on-peak would apply every day, holidays excluded. If that lands, you're covering the window on weekends too, which makes a properly sized battery more valuable, not less.
So — is it worth it for you?
It depends on three things, in order:
- Are you willing to switch to Rate 7? No switch, no savings. The switch carries commitments — a time-of-use plan, special metering — worth understanding before you sign. (How to switch to Rate 7, and what to confirm first →)
- Is your battery sized to cover your actual peak? This is what protects you from the demand charge. (What size you actually need →)
- What does your specific usage look like? Summer AC-heavy months save more than mild months. My $120 is one data point, not a promise for your house.
That's the honest version. No inflated payback, no "batteries pay for themselves overnight" — just the real lever (the rate switch), the real catch (the demand charge), and a real bill to back it up.
If you want your own numbers instead of mine, you can run your Dominion bill through the analyzer — upload it or type in your usage, and it works out your backup time, your savings on the rate switch, and a real system with honest pricing. No sales pressure, and it'll tell you plainly if a battery isn't worth it for your situation.