Guide
7kW or 22kW EV charger: which one can you actually use?
Updated
Two things have to be true before a 22kW charger does anything a 7kW charger does not, and most UK properties fail the first one.
Condition one: three phases at the property
22kW AC chargers draw across three phases. Almost all UK homes have a single phase supply, which is why 7kW units are the standard domestic product. You can tell by looking at the meter tails: one live and one neutral is single phase, three lives and a neutral is three phase. Upgrading a property to three phase is a job for the local distribution network operator, quoted through its own connection charging methodology, and it is a separate project with its own timescale rather than an accessory to a charger order.
Condition two: the car's onboard AC charger
AC charging is limited by the converter inside the vehicle, not by the wall unit. The maximum AC rate appears in the vehicle handbook, usually as the onboard charger rating. If the car accepts 7.4kW on AC, a 22kW charger delivers 7.4kW. If it accepts 11kW, it delivers 11kW. This is why a 22kW purchase should start with the handbook and not the product page, and why rapid public charging, which is DC and bypasses the onboard charger, behaves differently from anything you can fit at home.
What smart charging law requires either way
- Smart functionality is mandatory. A relevant charge point "must have smart functionality", able to send and receive information over a communications network and to increase, decrease or reschedule the flow of electricity (Electric Vehicles (Smart Charge Points) Regulations 2021, regulation 5).
- Default off-peak hours. The charge point must come with pre-set default charging hours outside peak, and peak is defined in the regulations as 8am to 11am and 4pm to 10pm on weekdays. You are given the chance to accept, remove or change them when it is first used.
- It must keep working offline. If it loses its connection to the communications network it must remain capable of charging a vehicle.
- Switching supplier must not break it. A charge point must not be configured so it loses smart functionality when the owner changes electricity supplier.
- Randomised delay. Charge points operate a random start delay of up to 600 seconds, which the owner can cancel, so that thousands of cars do not all start on the same tariff boundary.
The practical answer for most homes
A 7kW single phase unit with smart scheduling on an off-peak tariff. It replenishes a normal day's driving overnight, works within the existing supply, and avoids a network connection project. Reach for 22kW when the property already has three phases and the vehicle can use them, or when the site is a workplace with several vehicles turning over during the day.
The checker asks about your supply before it recommends anything, because that is the question that settles it.