"Should I get the 22kW charger instead of the 7kW?" is one of the most common questions we hear. The honest answer in 2026 is: almost certainly no. 22kW charging needs three-phase electrical supply (rare in UK homes), an EV that accepts 22kW AC (rare in 2026 — most max out at 11kW or even 7kW), and offers limited real-world benefit for most charging patterns. Here's the maths.
What "kW" actually means
A charger's kW rating is its maximum power output. The charging speed in real life is the lower of three things:
- The charger's max rate
- Your home electrical supply's capacity
- Your EV's on-board AC charger capacity
The third one is the binding constraint for most people. Plug a 22kW charger into a car with a 7kW on-board charger and you charge at... 7kW. The charger waits for the car.
Single-phase vs three-phase supply
UK homes have one of two electrical supplies:
- Single-phase: Standard 230V supply, typical max 23kW (100A). Supports up to 7.4kW EV charging.
- Three-phase: 400V supply, much higher total capacity. Supports up to 22kW EV charging.
Around 95% of UK homes are single-phase. Three-phase is more common on:
- Farms (especially Cornish dairy and grain farms)
- Converted commercial properties
- Some larger detached homes built post-2010
- Properties with electric forge/workshop history
- Some industrial-conversion holiday lets
Upgrading from single-phase to three-phase typically costs £3,000-£10,000 via the DNO (Western Power in Cornwall) and is rarely worth it for an EV charger alone.
Which EVs actually accept 22kW AC?
The on-board AC charger inside each EV has a max rate. Many UK-market EVs in 2026 max out at:
- 7.4kW single-phase only: Older Nissan Leaf, some entry trims of Renault Zoe
- 11kW three-phase (or 7.4kW single): Tesla Model 3/Y, VW ID.3/ID.4, BMW i4, Hyundai Ioniq 5, Kia EV6, Polestar 2 — the most common spec in 2026
- 22kW three-phase: Renault Megane E-Tech (high trim), older Renault Zoe (Q90), Audi e-tron GT, some Smart models, certain VW commercial variants
If your EV is in the middle group (11kW max), a 22kW charger gets you 11kW. If it's in the 7.4kW group, you get 7.4kW. Only the third group benefits from 22kW AC.
Real-world charging speeds
| Setup | Speed | Time for 50 kWh (typical full charge) |
|---|---|---|
| 3-pin plug (granny cable) | around 2.3 kW | 22 hours |
| 7.4 kW single-phase home charger | around 6.5-7 kW real | 7-8 hours |
| 11 kW three-phase home charger | around 10 kW real | 5 hours |
| 22 kW three-phase home charger | around 20 kW real | 2.5 hours |
| 50 kW public DC rapid | around 45 kW real | 1 hour |
| 150-350 kW public ultra-rapid | around 100-200 kW real | 15-30 minutes |
The overnight maths
Here's where the 7kW vs 22kW debate usually ends. A typical EV owner drives around 30 miles/day — that's about 7.5-8 kWh of consumption. Topping that up at 7kW takes just over an hour. On Intelligent Octopus Go's 6-hour off-peak window, you have plenty of slack.
Even on a long drive day (200 miles round trip, around 50 kWh used), a 7kW charger replaces that in 7-8 hours — comfortably within an 11pm-7am charging window.
22kW only helps if you regularly need to add 50+ kWh in less than 4 hours AND your car supports 22kW AND your house has three-phase supply. For 95% of UK households, the answer is "none of those apply".
When 22kW IS worth it
- Holiday let with multiple guest EVs. If you have a holiday cottage with a 22kW-capable supply, fitting a 22kW charger (load-managed) means a Renault Zoe or Megane guest can fast-charge in 2-3 hours and free the bay for the next guest. See our holiday let guide.
- Multi-EV household. Two cars on one supply — 22kW lets you charge both in sequence within one overnight window without compromise.
- Mixed fleet workplace. If you run a small business fleet with vans that need quick turnaround, 22kW pays off operationally.
- You have a 22kW-capable EV. Renault Megane E-Tech, Audi e-tron GT, older Renault Zoe Q90, some Smart EQ models. Check your spec.
Cost comparison
- 7.4kW single-phase install: £800-£1,200 fitted
- 11kW three-phase install (where supply exists): £1,200-£1,700 fitted
- 22kW three-phase install (where supply exists): £1,400-£2,200 fitted
- Single-phase to three-phase DNO upgrade: £3,000-£10,000 — almost never worth it for a domestic EV
Our recommendation
For 99% of UK home EV owners: a 7.4kW single-phase smart charger (Zappi, Ohme, Easee, Pod Point, Hypervolt) is the right choice. It matches your supply, matches your car (in most cases), provides ample overnight charging, and costs less to install. Save the £500-£1,000 you'd spend chasing 22kW and put it toward a battery upgrade or solar PV instead.
For commercial / holiday-let / multi-EV use cases on three-phase supplies: 22kW makes operational sense and is worth the installation premium.
Not sure what your home supply is, or whether your car supports 22kW? Submit your postcode and we'll match you with a vetted Cornwall installer who can survey your supply type and recommend the right charger.
Disclosure
EV Charger Cornwall is a lead-gen service connecting you with vetted local OZEV-approved installers across Cornwall.