Original research
Solar Battery Storage in Mount Pleasant, SC
When a battery pays under each local utility’s rules, and how the Town’s flood rules decide where it goes.
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How Mount Pleasant’s two utilities treat a home battery
| Dominion Energy SC (Solar Choice) | Berkeley Electric (Renewable Surplus Rider) | |
|---|---|---|
| Rate required | Rate 5 time-of-use | Non-demand, non-time-of-day rate |
| Peak price | 29.907¢/kWh, 4–8 p.m. in summer (May–Sep), 6–9 a.m. in winter | No peak window on eligible rates |
| Export value | Netted within each time-of-use period monthly; surplus paid at avoided cost each November | 6.03¢/kWh, updated about 1 March |
| Storage rule | Counts only if it charges solely from onsite renewables | Not addressed on the co-op’s renewable energy page |
| Main battery value | Shifting solar into the evening peak, plus backup | Backup, and storing solar for your own use instead of exporting at 6.03¢ |
Dominion Rider to Rate 5 (PSC Order No. 2026-374) and Rate 5; Berkeley Electric renewable energy page. Retrieved 5 October 2026.
What a battery earns on Dominion Rate 5 in Mount Pleasant
The gap between Rate 5 on-peak and off-peak is 14.833¢/kWh. Every kWh of midday solar a battery holds back and releases between 4 and 8 p.m. in summer is worth that difference.
As an example, 10 kWh shifted on 150 summer days is worth about $222 a year (10 × 150 × 14.833¢).
The inputs are examples: your own figure depends on battery size, how much the house draws in the evening, and winter, when the on-peak window moves to 6–9 a.m.
Winter mornings matter in Mount Pleasant homes with heat pumps: the 6–9 a.m. winter peak arrives before panels produce, so only stored energy from the previous afternoon can cover it. A battery set to reserve some charge overnight serves both windows.
Outage and storm backup for Mount Pleasant homes
Grid-tied solar alone shuts off in an outage for line-worker safety; a battery with a backup gateway keeps chosen circuits running and lets the panels recharge it.
The Town names two types of flooding: localized flooding from drainage, and storm surge from tropical storms and hurricanes.
NOAA’s Storm Events Database records 21 tornadoes and a peak gust of 83 knots in Charleston County from 2015 to 2025.
Whole-home or partial? A whole-home setup covers central air and pool equipment but needs more capacity.
A critical-loads panel covering the refrigerator, lights, Wi-Fi, a well or sump pump and a mini-split runs far longer on the same battery.
For multi-day outages after a hurricane, partial backup that the panels can recharge each day is the more resilient design.
Where to put a battery in a Mount Pleasant flood zone
Since 29 January 2021 the Town’s design flood elevation is base flood elevation plus 2 feet, and Coastal A zones are regulated like VE zones.
A battery on a garage slab in an AE zone can sit below that line.
Options are a wall mount above the design elevation, a raised platform, or an interior location on an upper floor where the product’s fire-safety listing and the code allow it.
The Town keeps elevation certificates for homes built in Special Flood Hazard Areas and will answer flood-zone questions; ask for yours before the design is drawn.
Sizing a battery for a Mount Pleasant home
Size from two numbers: the kWh your home draws in the evening peak window (from hourly usage data, if your utility account shows it) and the circuits you need during an outage.
Storage capacity beyond what your panels can refill on a sunny day adds cost without adding much value. The battery sizing tool walks through both.
A battery also adds an electrical review to the Town permit, and in a flood zone the elevation detail.
Battery cost, lifespan and warranty for Mount Pleasant buyers
We do not publish a battery price for Mount Pleasant until we hold dated local quotes.
Compare quotes on usable kWh, continuous power output in kW, round-trip efficiency, and the warranty’s years and throughput limit, whichever comes first.
Ask whether the warranty covers installation in a garage that reaches coastal summer temperatures, and whether the installer or the manufacturer handles claims.
Whether a battery qualifies for South Carolina’s 25% solar tax credit is something we could not confirm, so treat it as unknown when doing the maths. Financing a battery with the panels is covered on the Mount Pleasant financing page, and full system costs on the cost page.
Who in Mount Pleasant should and should not add a battery
Worth a close look
Dominion customers with high summer-evening use: pool pumps, second HVAC zones, EV charging after work.
Homes where anyone relies on powered medical equipment, or where outages after storms have lasted days.
Owners in flood zones who can mount equipment above the design flood elevation.
May not need one
Berkeley Electric members whose main goal is bill savings: no peak window to arbitrage on eligible rates.
Households that are out most evenings and can shift use to midday instead.
Homes where the only battery location is below the design flood elevation and raising it is impractical.
Questions
Is a solar battery worth it in Mount Pleasant?
Can my battery charge from the grid on Dominion’s Solar Choice?
Where should a battery go in a Mount Pleasant flood zone?
Will solar panels power my house during a hurricane outage?
Does Berkeley Electric pay more for battery-stored solar?
Does the SC tax credit cover batteries?
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