For almost every UK home the answer is 7kW: most domestic supplies are single-phase, so a 22kW charger physically can't run at full speed — and a 7kW install is both cheaper and faster to fit.
If you are speccing a home charger, the wattage choice looks like a simple speed upgrade: 22kW is three times the number on the box, so it must charge three times faster. In the real world it almost never works that way. The deciding factor is not the charger — it is the electricity supply already coming into your house, and for the overwhelming majority of UK homes that supply caps you at around 7kW no matter which unit you bolt to the wall.
Below we break down what 3kW, 7kW and 22kW actually mean, why single-phase versus three-phase power is the real fork in the road, what the cost gap looks like against live UK install figures, and the one simple rule that tells you which to choose.
3kW vs 7kW vs 22kW: what the numbers really mean
The kW figure is the rate at which a charger can push energy into your car. A 3kW charger is essentially a glorified plug — it trickles in roughly 8–10 miles of range per hour. A 7kW unit, the UK home standard, adds around 25–30 miles of range per hour, enough to fully refill almost any EV overnight. A 22kW charger can in theory add 80–90 miles per hour — but only if your home can physically deliver that power, and most cannot.
Crucially, the car has its own limit too. Many popular EVs accept a maximum of 7.4kW or 11kW of AC charging at home; feed a 7.4kW-limited car a 22kW charger and it still draws only 7.4kW. So even where 22kW is available, a large share of cars throttle it back to roughly 7kW anyway — you would be paying for headroom the vehicle never uses.
Single-phase vs three-phase: the real reason most homes pick 7kW
Here is the part that decides almost everything. A standard UK domestic supply is single-phase, rated at about 100A — which works out to roughly 7.4kW of usable power for a charger once the rest of the house is accounted for. That is exactly why 7kW became the home standard: it is the most a single-phase house can sensibly hand to a car.
A 22kW charger needs a three-phase supply, the kind of connection found in factories, large commercial units and a small minority of newer or rural homes. If you only have single-phase power and install a 22kW charger, it physically cannot run above ~7kW — you have bought a 22kW unit that behaves like a 7kW one.
Getting three-phase power installed means asking your Distribution Network Operator (DNO) to upgrade the supply, which can involve digging up the driveway or pavement, new cabling from the street, and a new meter arrangement. Quotes for a domestic three-phase upgrade commonly run into the thousands of pounds and can take weeks or months to schedule — before you have even paid for the charger itself.
The real cost difference (using live UK install data)
A standard 7kW home install is a fixed, well-understood job. Our live UK cost index currently puts the average 7kW install at £1,073, with most jobs landing across the tracked low-to-high range. For market context, independent figures echo this band: tradesperson network Checkatrade has cited a typical EV charger install around £1,000, energy supplier E.ON Next has advertised installs from about £1,272, and recent UK quotes shared on Reddit cluster near a £999 floor. (Those are other companies' figures, quoted as market context — the live average above is what UK installs are actually tracking at right now.)
A 22kW home install on single-phase power costs broadly the same as a 7kW install for the unit and labour — but delivers no extra real-world speed, because the supply caps it at ~7kW. To unlock genuine 22kW you must add a three-phase supply upgrade on top, which is where the cost balloons into the thousands. So the honest comparison is not '7kW unit vs 22kW unit' — it is 'a £1,073-ish 7kW job' versus 'that same job plus a four-figure network upgrade for speed your car may not even accept'.
Want a figure for your exact property — cable run, consumer unit, the lot? Run the numbers with our install cost calculator rather than relying on a national average.
What 7kW actually means for overnight charging
The speed anxiety behind '22kW must be better' usually evaporates once you do the overnight maths. At 7kW you add roughly 25–30 miles of range per hour. Plug in at 6pm and unplug at 7am and you have had about 13 hours on charge — comfortably 300+ miles of range added, far more than the average UK driver covers in a day (around 20 miles).
In other words, the bottleneck is how long your car sits on the driveway, not how fast the charger pushes. A 22kW charger finishes sooner, but if you are asleep either way, the extra speed buys you nothing. Pair a 7kW smart charger with a cheap overnight EV tariff and you wake up full, for pennies, every night.
When is a 22kW charger actually worth it?
There are genuine cases for 22kW — they are just rare at home. It earns its keep if you already have a three-phase supply (so there is no expensive upgrade), drive very high daily mileage with short windows to charge, run two EVs sharing one charger, or have a car that genuinely accepts 11kW+ AC charging. For a fleet yard or a business forecourt, 22kW is often the right call.
For a typical single-car household with off-street parking and a normal commute, none of that applies — which is why, for almost everyone, 7kW is the sensible, cheaper, faster-to-install choice. See the full side-by-side on our 7kW vs 22kW comparison.
The simple decision rule
Choose 7kW unless you can tick a three-phase supply you already own and a real need for faster-than-overnight charging. If you only have single-phase power — which means most UK homes — a 22kW charger cannot run at 22kW anyway, so you would be paying for a number on a box, plus potentially thousands for a supply upgrade, to gain speed your car may not even accept and your sleep schedule does not need.