DC Rapid vs AC Fast Chargers for Business: Which Should You Install?
A side-by-side comparison of AC fast and DC rapid EV chargers for UK businesses — cost, dwell time, grid impact, ROI and how to choose the right mix.
The single most common question we get from UK businesses planning EV charging: "Should we install AC fast chargers or DC rapid?" The honest answer for most sites is both, in the right ratio — but the wrong split wastes capital and frustrates drivers.
Here's how to decide, in plain numbers.
The core difference
- AC fast (7–22kW): charger sits between the grid and the car; the car's own onboard charger converts AC to DC. Capped by what the car accepts (most EVs: 7–11kW AC).
- DC rapid (50–350kW): the charger converts AC to DC on-site and feeds the battery directly, bypassing the car's onboard charger. Speed limited by the battery and the cable, not the car's AC limit.
Side-by-side comparison
| Factor | AC Fast (7–22kW) | DC Rapid (50–150kW) |
|---|---|---|
| Installed cost / bay | £1,200–£4,500 | £30,000–£60,000 |
| Time to add 100 miles | 1.5–3 hrs | 10–20 mins |
| Typical dwell match | Workplace, hotel, BTR, gym | Forecourt, retail, fleet depot turnaround |
| Grid capacity needed | ~32A per 7kW bay | ~150–400A per 50kW unit |
| DNO upgrade risk | Low | High — almost always G99 |
| Revenue / bay / day | £2–£12 | £40–£180 |
| Hardware lifespan | 10–12 years | 7–10 years |
When AC fast is right
If drivers are parked for 2+ hours anyway, AC fast wins on every metric. Workplaces, hotels, residential BTR, gyms, cinemas, golf clubs — all dwell-driven. You can install 10× the bay count of a DC scheme for the same capex, and your DNO almost always approves the load.
The hidden AC advantage: scale
£100,000 of capex buys ~30 AC bays or ~2.5 DC rapids. Thirty bays at 60% utilisation serves 60+ vehicles a day; 2 DC rapids at the same utilisation serve ~50. For most non-forecourt sites, AC delivers more useful kWh per pound spent.
When DC rapid is right
- Retail forecourts — drivers won't wait 2 hours for groceries.
- Fleet depots with mid-shift turnaround — a 30-minute top-up at lunch transforms route planning.
- Motorway-adjacent destinations — top-up culture, short dwell.
- Taxi / private hire ranks — earnings stop while charging; speed is income.
The blended ratio that usually wins
For most multi-purpose commercial sites (mixed retail, leisure, light fleet), the sweet spot we model is:
- 70–80% of bays at 22kW AC for dwell-time users (staff, regulars, long-stay).
- 20–30% as 50kW DC for transient users and overflow.
- 0–1 ultra-rapid (150kW+) only if the site is on a strategic route and DNO capacity allows.
Grid and DNO impact
A 6-bay 22kW AC scheme draws ~132kW peak — usually within existing supply. A single 150kW DC rapid draws 150kW continuously, almost guaranteeing a G99 DNO application and often a supply upgrade. Read our DNO application guide before committing to DC.
Total cost of ownership over 8 years
On a like-for-like utilisation basis, AC fast typically delivers £0.18–£0.28 net profit per kWh vs DC rapid at £0.10–£0.20 — DC's higher tariff is offset by higher hardware depreciation, demand charges and back-office fees. DC wins on absolute revenue per bay; AC wins on ROI per pound of capex.
The decision in one sentence
Match charger speed to driver dwell time — not to what sounds impressive in the brochure. If your visitors stay 90 minutes or more, AC almost always wins the business case. If they stay under 30 minutes, DC is the only option that works.
Want a costed AC-vs-DC mix for your specific site? Run the variables in our free feasibility calculator or compare with our UK install cost guide.