Understanding home charging costs and speeds

Why home charging changes the whole cost picture

For most drivers, the cheapest and most convenient place to charge an electric car is the driveway. Public rapid chargers are brilliant on a long trip, but at somewhere between 50p and 80p per kilowatt hour they can end up costing more per mile than petrol. Charging at home, on the right tariff, typically works out at a third or a quarter of that. In the West Country, where many of us have a driveway or a bit of space beside the house, that advantage is easy to capture — provided the installation is done well and the timing is right.

This guide covers what a home charge point can actually deliver, what it costs to run, and the practical details that catch people out in Devon, Cornwall, Somerset, Dorset, Wiltshire and around Bristol and Bath.

Three-pin plug versus wall box: the speed difference

A standard domestic socket delivers roughly 2.3 kW. On a typical electric car that's around 8 to 10 miles of range per hour, so a 60 kWh battery might take the best part of a day to fill. It works, and plenty of people manage on it, but it's slow and it isn't really designed for the job — a socket running at full load for eight hours at a time gets warm, and you should have the circuit checked by an electrician before relying on it as your main charging method.

A dedicated wall box on a single-phase supply typically delivers 7.4 kW. That's roughly 25 to 30 miles of range per hour, which means:

• A 40 kWh battery goes from 20% to 80% in about three and a half hours.
• A 60 kWh battery does the same in roughly five hours.
• A 77 kWh battery takes around six and a half hours — comfortably an overnight job.

Some homes with a three-phase supply can run an 11 kW unit, and a few cars will accept it. Check what your car's onboard charger can actually take: a car limited to 7.4 kW won't charge any faster from a more powerful box, no matter what's bolted to the wall.

What it costs, and why the tariff matters more than the hardware

A wall box doesn't reduce your unit rate — the tariff does. On a standard variable rate of around 24 to 26p per kWh, a full charge of a 60 kWh battery costs roughly £14. On an EV-specific tariff with an off-peak window at something like 7 to 10p per kWh, the same charge costs £4 to £6, provided you let the car charge overnight rather than plugging in at teatime.

Per mile, that's often 2 to 4p at home against 14 to 16p for a petrol car doing 45 mpg. Over 8,000 miles a year, the difference runs well into four figures. The catch is that these tariffs usually come with a higher daytime rate, so they suit households that can shift most of their usage — washing machine, dishwasher, car — into the cheap hours.

• Off-peak windows are commonly four to six hours long, often in the early hours.
• Smart charging lets the car and the charge point talk to your supplier, so you get the cheap rate without setting an alarm.
• Timed charging built into the car works just as well, if the software behaves itself.

Before a long run down to Cornwall, charge to 100% at home the night before. The first 150 miles or so cost you pennies, and you'll only need a rapid top-up if you're heading beyond your car's comfortable range.

Practicalities for West Country homes

Rural properties bring their own considerations. A long driveway may mean a cable run of 30 metres or more, and voltage drop over that distance can be significant — your installer may need a heavier cable, which adds cost but avoids a slow, disappointing charge. If the parking spot is a barn or garage away from the house, run the supply properly the first time rather than relying on an extension lead.

Earthing is the other thing to raise. Many supplies are of a type that requires either an earth rod or a charge point with built-in protection against a lost neutral. A competent installer will check this as a matter of course; if yours doesn't ask, that's a warning sign. If your supply is already close to capacity, load management can throttle the charge point when the oven and immersion heater are on, which is usually far cheaper than a supply upgrade. Your installer will normally notify the network operator about the new load.

For terraced streets in Bristol, Bath or Exeter, where off-street parking is scarce, a wall box may not be possible. In that case, look at whether your council has installed on-street charge points nearby, and check whether you qualify for grant support as a renter or flat owner.

Solar, batteries and smart timing

If you have solar panels, charging the car during daylight uses power that would otherwise be exported for a few pence. A diverter, or a charge point that follows your generation, can soak up the surplus. Pairing that with an off-peak tariff gives you the best of both — sun in summer, cheap grid power in winter.

Home batteries are worth considering if you do a lot of daytime driving, though the losses involved in charging a battery to charge a car mean the savings are usually modest. Run the numbers on your own mileage before spending.

Worth doing properly

Choose a charge point with a cable long enough to reach where you actually park, and think about whether you want it tethered or untethered. Keep the installation certificate, the invoice and any grant paperwork with the car's documents. When you come to sell, a buyer with a home charger already fitted has a genuine incentive, and evidence that it was installed to standard by a qualified electrician is quietly reassuring.

Get the wiring, the earthing and the tariff right at the start, and home charging becomes the quiet background habit that makes electric motoring genuinely cheap. Get it wrong, and you'll spend your evenings watching an app and your mornings at a motorway services.