- 11kW chargers are 57% faster than 7kW chargers
- Installation requires a three-phase power supply (most homes are single-phase)
- Upgrading from single to three-phase is relatively easy for competent electricians
- More car manufacturers are giving their vehicles 11kW onboard chargers, so it is worth considering for future proofing
In the UK, most houses have a single-phase power supply. The ‘phase’ refers to the distribution of the electric load. Single-phase power handles less load than 3-phase power, and the maximum safe charge speed is usually 7.4kW.
A 7.4kW charger adds around 30-miles of range per hour in optimal conditions, but what if you want to charge even faster?
For that, you need a 3-phase power supply.
You can’t get 3-phase power at home without upgrading your electrics, which requires upgrading the main fuse and modifications to the cabling supplying your property.
Although it can be expensive to convert from single to 3-phase, it will give you the ability to charge at 11kW at home, adding 38-miles of range per hour.
Is 11kW worth it over 7.4kW?
The question of whether an 11kW home charger is worth the extra cost over a 7.4kW home charger depends on whether the extra charge speed appeals to you.
11kw is 57% faster than 7kW, so there is a perceptible difference in charge speeds.
Let’s look at an example:
- Your car battery is 60kWh. Charging from 0-100% with a 7.4kW charger will take 8 hours 10 minutes.
- Charging the same car with an 11kW charger will take 5 hours 45 minutes – an improvement of over 3 hours or so.
- The 7.4kW charger adds around 30-miles of range per hour, while the 11kW charger adds around 38-miles of range per hour.
From a futureproofing perspective, more electric cars are supporting 11kW AC charging, and it is inevitable that as costs come down, all of them will.
Ultimately, an extra 8-miles of range per hour is a decent boost, but if you charge overnight, then it is unlikely the extra speed will benefit you.
Most EV chargers installed in homes are 7kW to 7.4kW. These chargers are more than twice as fast as cheaper 3.6kW chargers and offer good value for money. 11kW chargers are more expensive, typically around 25% more expensive.
If you charge at night, the faster charge speed is clearly not beneficial. However, when topping up during the day, it equates to an extra 8 miles of range per hour – this could be the difference between charging on a trip out or not.
Home charger speed table
Time to charge with different charging points:
|Charge speed (up to)||25 miles per hour||28 miles per hour||30 miles per hour||38 miles per hour|
The bottom line: 11kW chargers are 57% faster than 7kW chargers!
Can I have an 11kW charger at home?
The short answer is yes, you can have an 11kW charger at home. You will need a 3-phase power supply and a charger that supports 11kW charge speeds. Electricians can handle the electrical work but they are not allowed to change the supply, which must be done by the distribution network operator (DNO).
We asked eco-EV Ltd, a charge point installer in Hull, about the work required to convert a single-phase power supply into a three-phase power supply:
“Three-phase installations are structurally different to single-phase, so the existing single-phase fuse and cabling running to the property need replacing. In most homes, in the case of cabling, this means trenching [digging] back.”
“Trenching is time-intensive, sometimes at a depth of 60cm for several metres. We need a trench to make a line for the new cabling and to connect that cabling to the 3-phase supply. Sometimes you get lucky and the supply is only a few metres away, but there isn’t always a 3-phase supply located nearby.”
“Thankfully, the existing wiring in a modern house is compatible with a three-phase supply, so really, only the cabling supplying the property needs upgrading along with the distribution board.” Paul adds, “the unit needs replacing with a three-phase distribution board with RCD protection, to meet regulations.”
Read our article about converting to 3-phase for costs and work details.
11kW charging gives you 38-miles of range per hour versus 30-miles at 7.4kW, letting you charge a lot faster. As EV batteries get bigger, your requirement for faster charging is likely to increase, so 11kW is worth it if you can afford it.
However, 7kW is enough for an EV. If you charge overnight, the additional 8-miles of range from 11kW is unlikely to improve your ownership experience.