Fitting an EV charger to a street-front wall
A 7.2 kW charger on the front wall charged roughly 2,100 kWh into the household's car in 2025. Charged overnight on a cheap rate, the homeowner estimates a 125-mile round trip to London at about £3, against about £21 to £22 in a petrol or diesel car (an illustration, not a bill). Over 2025 charging the car would have cost about £270 at the house's average price per unit, or about £150 at the overnight rate, against about £1,200 of petrol for the same miles. The charger shares its wall with a broadband box, an isolator and a downpipe, which shows the practical side of fitting equipment to an older house.
What is on the wall
A SolaX 7.2 kW charger is fixed to the front brick wall near the right-hand end, beside the party wall and the downpipe, about a metre above the pavement. It was installed in October 2024, together with a third battery module, for £2,335 between them, with no grant or VAT relief. Close by are a brown CityFibre broadband box, which is not part of the energy system, and a small isolator switch. It is on the front wall because the street in front is the only place the car can park. Much of the household's own money for its retrofit measures came from the solar panels' Feed-in Tariff, described in the solar story.
How the car connects
The charger is "untethered": it has no cable of its own, so the household plugs in its own 10 m lead. The silver Renault Zoe E-Tech parks on the street in front of the right half of the house, about 5 m out, with its nose towards the wall because its charging port is at the front. The lead runs out to it.
What a trip costs
A 125-mile round trip to London takes about 36 to 42 kWh, at roughly 3 to 3.5 miles per kWh, a sensible everyday figure for a Zoe of this kind. Charged overnight at Intelligent Go's cheap rate, published at about 7 to 8 pence a unit, that comes to about £2.50 to £3.30: around £3 for the whole trip, by the homeowner's own estimate. The same 125 miles in a petrol car doing 45 miles to the gallon, at about 174p a litre, would cost about £22; in a diesel doing 55 miles to the gallon, at about 199p a litre, about £21. That is roughly seven times as much as the electric trip. These are illustrative sums, not bills: they use a published cheap rate, typical fuel economy and one tracker's average pump prices for the week to 11 October 2026, and the real cost depends on the rate, the weather, the driving and the price on the day.
What it charged in 2025
The charger's app shows roughly 2,100 kWh delivered to the car in 2025, from about 65 kWh in November to about 270 kWh in March and October, read by eye from its yearly chart, so each month is approximate. Much of it came from regular drives to London for work, with the car charged overnight. The household uses cheap overnight rates on Octopus's Intelligent Go tariff and also tries to make the most of the sun and the battery. The app shows what the charger delivered, not whether the energy came from the grid, the solar panels or the battery.
What it cost in 2025
At the 13p a unit that the house's whole electricity bill averaged out at, standing charge included, the roughly 2,100 kWh the car took would cost about £270. If all of it had been bought at the cheap overnight rate of 7p a unit it would be about £150, and charge that came from the roof cost nothing, so the real cost may be lower still. These are pricing examples, not the actual 2025 cost, which the charger's app does not record. Over about 6,800 miles (at 3.25 miles per kWh) they come to about 2 to 4p a mile. The same miles in a petrol car doing 45 miles to the gallon, at about 174p a litre, would cost about £1,200 in fuel, about 18p a mile. These are illustrations, not bills.
Fitting equipment to this house
What was specific to this house: a front wall on the street, a party wall on one side and services already on the wall. The charger, the isolator and the broadband box share a small patch of brick near the end of the wall. Any charger needs a power supply route, a mounting spot near where the car stands, and a way to connect to it; the choices that suit one house will not suit another.
Putting the figures in proportion
The 2,100 kWh the car took is nearly twice the roughly 1,150 kWh the heat pump's app reports for the same year. Both are the apps' own estimates, and neither says where the energy came from, so they are not added to a household total here.
Carbon, roughly
At the UK government's 2025 factors, the 36 to 42 kWh a 125-mile round trip uses is about 6.5 to 7.5 kg of CO2e on the UK grid average (0.177 kg per kWh). The same trip in a petrol car at 45 miles to the gallon is about 12.6 litres, about 26 kg (2.069 kg per litre), and in a diesel at 55 miles to the gallon about 10.3 litres, about 27 kg (2.571 kg per litre). Over 2025 the roughly 2,100 kWh the charger delivered is about 370 kg; the same miles (about 6,800, at 3.25 miles per kWh) in a 45 mpg petrol car would be about 1,430 kg. These are illustrations, not measurements: any of the car's charge that came from the solar panels counts as less, and the factors exclude the energy used to make fuel or electricity. The battery's effect on carbon cannot be determined from the available data: it can charge from the panels or from the grid, the split is not recorded, and storing energy loses some of it.
Benefits
- Charging at home overnight on a cheap rate: about £3 for a 125-mile round trip, on the homeowner's estimate (an illustration, not a bill), against about £21 to £22 in a petrol or diesel car.
- Cheap miles: about £270 to charge the car for 2025 at the house's average price per unit, about £150 at the overnight rate (and less for anything charged from the roof), about 2 to 4p a mile, against about £1,200 of petrol for the same 6,800 miles, about 18p a mile (an illustration, not a bill).
- Lower carbon per trip: about 7 kg of CO2e for the 125-mile round trip on the UK grid average, against about 26 kg in a petrol or diesel car (an illustration; see the carbon note).
- Charging at home overnight, from the same supply as the rest of the house.
- A charger that stays out of the way: a small box on the front wall.
Limitations
- This is one house's choices: the charger is where the car can park, which will differ for another home.
- The charging figure is read by eye from the charger app's chart and is not a meter reading.
- The trip cost is the homeowner's own estimate, from a published rate, typical fuel economy and one tracker's pump prices, not a bill. No payback is claimed, and the carbon figures are approximate illustrations, not measurements.
- The cable arrangement is the household's own and not general advice.
- The yearly cost is a pricing example, not a record: the charger's app does not say when or from what the energy came, so £270 (the house's average price) and £150 (all at the overnight rate) are examples, and the real cost may be lower where the roof supplied it; the petrol figure is an illustration using typical economy and one tracker's pump price, and no payback is claimed.
References
- Octopus Energy: Intelligent Octopus Go rates, January 2025 table (7p per kWh off-peak; other published figures for 2026 are about 7 to 8p). Rates change and differ by region.
- Fuel Finder UK: weekly price pulse, week ending 11 October 2026 (a private tracker, not government figures: petrol E10 about 174p, diesel about 199p a litre)
- DriveElectric: Renault Zoe Techno R135 listing, real-world range and efficiency (about 3.1 miles per kWh; other road tests suggest 3 to 3.5)
- UK Government: Greenhouse gas reporting, conversion factors 2025 (UK electricity 0.177 kg CO2e per kWh, natural gas 0.183 kg per kWh gross, petrol 2.069 kg and diesel 2.571 kg per litre; electricity excludes transmission losses and on-site solar counts as zero)