For most UK homes, the choice between a 7kW and a 22kW EV charger is settled by the electricity supply before personal preference gets a look in: 22kW charging needs a three-phase supply, the overwhelming majority of UK houses have single-phase, and many cars cannot accept 22kW AC anyway. That makes the honest answer short — 7kW for most homes — but the reasoning is worth having, because it protects you from paying for a number you can never use. Here is how to read your own supply, what the figures actually mean, and the narrow cases where 22kW earns its keep.
What the numbers actually mean
Charger ratings are just current and voltage multiplied. A standard UK house has a single-phase supply at 230 volts, and a dedicated home chargepoint draws 32 amps on it: 32 × 230 gives about 7.4kW, marketed as 7kW. A 22kW charger draws that same 32 amps — but across three phases at once, which is why it needs a three-phase supply rather than a beefier version of a normal one.
For scale at the other end: charging through a standard 3-pin socket (so-called granny charging) runs at around 2.3kW, and a domestic socket is not designed for that load sustained overnight, night after night. A dedicated 7kW unit is roughly three times faster and built for the job — which is the genuinely important upgrade. The step from 7kW to 22kW, by contrast, only exists for homes whose wiring and car can both use it.
Your car has a vote too
Here is the part the brochure comparison misses: AC charging speed is capped by the car’s on-board charger, not just the wallbox. Many EVs accept no more than 7.4kW AC — plug one into a 22kW unit and it charges at exactly the speed it would on a 7kW unit. Some cars accept more, and the specification sheet for your exact model (not the range) is where the truth lives. We check it before quoting, because selling a 22kW charger to the owner of a 7.4kW-limited car is selling a bigger number, not faster charging. The same check protects you in the other direction: if the car you are planning to buy next accepts a higher rate, better to know before the unit goes on the wall.
Public rapid chargers escape this ceiling by using DC charging at power levels a domestic supply cannot provide — a different tool for long-distance top-ups, not overnight charging at home.
Your main fuse, and what the network allows
Between the charger and the three-phase question sits a quieter constraint: your main fuse. A 7kW charger is a significant continuous load on top of everything else the house draws, so the survey checks your fuse rating and spare capacity before anything is promised.
The useful news is that the network side is more flexible than people expect. UK Power Networks — the distribution operator covering London, the South East and the East of England — publishes that it can upgrade a domestic main fuse from 30 or 60 amps up to 80 or 100 amps, and that where your installer has applied to connect a charger through the network’s process, you may be able to have the device installed before a fuse upgrade, or may not need one at all. That application is part of the installation job — handled for you, not homework.
Two wrinkles are worth knowing. If your supply turns out to be looped — shared with next door, something operators discover during exactly this sort of visit — the network re-plans the work with both households and there may be a charge. And practices vary between the regional operators, which is one more reason the survey, not a website, should settle what your home can take.
Charge-time arithmetic, honestly
The sums are worth doing once, with the assumptions visible:
- At 2.3kW (3-pin socket): a 60kWh battery from near-empty is a 26-hour proposition — fine as an occasional fallback, hopeless as a routine.
- At 7kW: the same battery takes roughly 8–9 hours, which is precisely what an overnight window is for. A typical day’s driving — a commute, a school run — goes back in within an hour or two.
- At 22kW: arithmetic says under three hours, if your car accepts 22kW AC. Most don’t, and for a car parked at home all night, the six hours saved are hours you were asleep for.
That last line is the crux. Speed you cannot use — because the car caps it — or do not need — because the car sits idle overnight regardless — is not a feature. It is just spend.
When 22kW genuinely makes sense
There are real cases. A property that already has a three-phase supply — some larger or converted buildings do — loses the biggest cost barrier at a stroke. A household running two EVs with high combined mileage can find fast turnarounds genuinely useful. And a car whose on-board charger accepts high AC rates can at least use what the unit offers.
If that is you, the kit exists: the EnSmart SmartBee-M range we fit is published in both 7kW single-phase and 22kW three-phase versions. But the order of operations does not change — supply first, car second, charger last. Commissioning a three-phase conversion purely for charging speed is a significant network job, and we would want you to price it against how often the extra speed would actually be used before committing. If the honest answer is “a few times a year”, keep the money.
One supply, several loads: designing the whole system
A charger rarely arrives alone these days. Households adding an EV are often the same households adding solar and battery storage, and all of it draws on — or feeds — the same supply. That is a design question, not a shopping list: the smart charger schedules into cheap overnight windows by law-mandated default, a home battery has its own charge and discharge rates the system must account for, and on sunny days surplus generation can go into the car instead of the grid. One survey that sees the whole picture beats three separate installations that each assumed they had the supply to themselves.
The wider job — survey, dedicated circuit, network notification, commissioning — is set out on our home EV charger installation page, and what the work tends to cost (and why nobody honest quotes it sight-unseen) is covered in our guide to EV charger installation costs. If a grant might apply to you, check who still qualifies in 2026 before anyone quotes you figures.
The short version
Buy the speed your supply and your car can actually use. For most UK homes that is 7kW — not as a compromise, but as the correct answer to the arithmetic. Nor does a 7kW unit date badly: a faster future car will draw what the supply allows, exactly as today’s does. If you think your home might be the exception, the survey settles it with evidence: request a free quote or call 0204 547 1892, and we will check the supply, the fuse and the car before recommending anything. No pressure, just clear advice.