A 7 kW home charge point is often the right answer, but it is not automatically the right answer for every property. Knowing how to size EV charger equipment properly means looking beyond the car brochure. Your vehicle, daily driving, available electrical supply, parking arrangements and plans for solar all matter – and a sensible choice can save unnecessary cost while making everyday charging straightforward.
There is also a small technical distinction worth knowing. The unit on the wall is usually called a charge point, while the charger itself is built into most electric cars. In normal conversation, though, ‘EV charger’ is widely understood, so we will use it here.
How to size EV charger power for daily driving
Start with the energy you actually need to replace, rather than the largest charging figure you can find. Most home charging happens while the car is parked overnight, which gives a useful window of eight to 12 hours without needing particularly high power.
A typical electric car uses roughly 0.25 to 0.35 kWh per mile in mixed UK driving. If you drive 30 miles on an average day, you may need around 8 to 11 kWh to put that energy back into the battery. Allowing for charging losses and cold weather, planning for 12 kWh is sensible.
A 3.6 kW charge point can deliver about 25 to 30 kWh over an eight-hour overnight period. A 7.4 kW unit can deliver roughly 50 to 60 kWh in the same time. For many households, either would comfortably cover ordinary commuting. The question is whether the extra speed of a 7.4 kW unit will be useful often enough to justify it.
If the car is regularly needed again after a short stop at home, or two drivers share one charge point, 7.4 kW gives more flexibility. If the car is parked from evening until morning and mileage is modest, 3.6 kW may be entirely adequate. Faster is convenient, but it is not always better value.
Check what the car can accept
The vehicle’s maximum AC charging rate sets a practical limit. Many electric cars can accept up to 7.4 kW on a single-phase home supply, but some plug-in hybrids and older EVs are limited to 3.6 kW. Installing a 7.4 kW charge point for a car that only accepts 3.6 kW will not make that car charge faster.
This does not always make the larger unit a poor choice. You may change cars in a few years, and a 7.4 kW charge point can future-proof the installation where the supply allows. It simply needs to be a conscious decision rather than an assumption.
Rapid chargers at motorway services work differently. They use DC power at much higher rates and are not comparable with domestic charging. Home charging is generally about convenient, lower-cost replenishment while the vehicle is already parked.
Your home’s electrical supply is just as important
Most homes in Kent have a single-phase supply. A 7.4 kW charge point draws up to 32 amps, which is a significant continuous load alongside cooking, showers, heat pumps and other household demand.
An installer should assess the incoming supply, main fuse rating, consumer unit, earthing arrangement and likely maximum demand before recommending a charge point size. This is not a box-ticking exercise. In some homes, a 7.4 kW unit can be installed without difficulty; in others, the existing supply or consumer unit needs attention first.
Modern smart charge points can use load balancing. This monitors household demand and temporarily reduces the car’s charging rate when the property is using more electricity elsewhere. For example, charging may slow while an electric shower is running, then increase again once demand drops. It helps protect the supply without asking you to manually manage appliances.
Where the supply is restricted, a 3.6 kW installation or a load-managed 7.4 kW installation may be the sensible route. In certain cases, the Distribution Network Operator may need to be notified or asked about upgrading capacity. A proper site survey identifies this before work begins, not after the charge point has been selected.
Do not rely on a standard three-pin socket
A portable charging lead from a standard 13-amp socket can be useful occasionally, particularly when visiting family or staying somewhere without a charge point. It is not usually the best long-term home solution.
It charges at around 2.3 kW, can take much longer to replenish the battery, and puts a sustained load on a circuit not necessarily intended for regular EV charging. A dedicated charge point is designed for the task, correctly protected and professionally installed.
Consider where and when you will charge
The location affects the right specification as much as the power rating. A driveway installation may suit a tethered unit with a fixed lead, while a detached garage or shared parking arrangement may call for a socketed unit, longer cable route or additional protection from accidental damage.
Cable length deserves a little thought. It should reach the vehicle charging port without trailing across a pavement or being stretched tightly around the car. Longer cable runs can increase installation complexity, so the best position is not always simply the closest wall to the consumer unit.
Think about future use as well. If a second EV is likely, it may be worth allowing capacity and cable routes for another charge point now. Installing two 7.4 kW units does not mean both can always run at full output. With intelligent load management, they can share the available power fairly, which is often more practical than arranging a costly supply upgrade immediately.
Solar panels can change the calculation
For homes with solar PV, a smart charge point can be set to charge from surplus generation, follow a schedule, or combine solar surplus with grid power to maintain a chosen minimum rate. This can make daytime charging particularly worthwhile for people who work from home or have a car parked on the drive during the day.
Solar output is variable, however. A 4 kW solar array rarely produces a constant 4 kW, and output falls sharply in winter or under cloud. A charge point should not be sized solely around the peak solar rating. It still needs to meet your normal charging needs when solar generation is low.
A 7.4 kW charge point does not force the car to take 7.4 kW at all times. With suitable controls, it can reduce its output to follow available solar surplus. That gives useful flexibility: charge gently from excess generation when conditions allow, then charge overnight on an off-peak tariff when the next day’s journey matters more than waiting for sunshine.
Battery storage adds another consideration. It can help retain solar energy for household use, but charging a car from a home battery is not always the most efficient or economical approach once conversion losses and battery cycling are considered. The best settings depend on battery size, tariff, solar generation and driving habits.
Choose smart controls, not just a higher kW rating
A good domestic charge point should make charging cheaper and easier, not add another system to manage. Look for scheduling that works with your electricity tariff, app control that is straightforward rather than gimmicky, and load balancing where the home supply requires it.
Reliability also matters. The charge point is exposed to weather, daily use and occasional knocks, so correct mounting, cable routing and electrical protection are every bit as important as the name on the front. Documentation, testing and clear handover should form part of the installation.
For most homeowners, the decision comes down to a properly surveyed 3.6 kW or 7.4 kW smart charge point. The right choice is the one that fits the vehicle, the household supply and the way you live – with enough headroom for the future, but without paying for capacity you will not use.
If you are weighing up an EV charger alongside solar or battery storage, a site visit from an experienced local installer can turn a confusing set of figures into a clear plan. Baird And Brown Ltd can assess the whole property so the finished installation is safe, tidy and suited to the way your home actually uses energy.
