Two numbers frame the whole question. PVGIS 5.3, the European Commission’s solar calculator, gives a 4 kWp south-facing array in Dunstable about 479 kWh in June and about 135 kWh in December. One is three and a half times the other, and the car’s charging needs barely change between them. This guide works through what that gap means for charging an electric car from a Dunstable roof, month by month, with the daily figures as our own arithmetic. For the charger itself, see our Dunstable EV charger installation page.
The figures are for an unshaded roof facing due south at 35°, with 14% system losses. East- or west-facing roofs make less, and shading changes the answer more than the town does.
Four months from one roof
| Month | PVGIS, 4 kWp in Dunstable | Average per day (our arithmetic) |
|---|---|---|
| June | about 479 kWh | about 16.0 kWh |
| July | about 482 kWh | about 15.5 kWh |
| December | about 135 kWh | about 4.4 kWh |
| January | about 154 kWh | about 5.0 kWh |
Across the whole year PVGIS gives about 3,962 kWh. Against Ofgem’s typical household use of 2,500 kWh a year, that looks like plenty to spare. The table shows why it is not that simple: the spare arrives in summer and the shortfall in winter, and a car needs charging in both.
A June day, worked through
Ofgem’s typical domestic consumption value is 2,500 kWh a year, about 6.8 kWh a day on our arithmetic. Suppose, to be cautious, that a Dunstable house used a whole day’s share in daylight. On an average June day the array’s 16.0 kWh would still leave about 9 kWh. A 7 kW charger takes about 7 kWh an hour, so that is roughly an hour and twenty minutes of charging (our arithmetic). July is close behind, at about 8.7 kWh to spare.
That is a top-up, not a full charge, and it only reaches the car if the car is plugged in while the sun is up. Some days are cloudier than the average and some are brighter; PVGIS gives the average over 2005 to 2023, not a promise for any given day.
A December day
In December the same roof makes about 4.4 kWh a day, below the house’s own 6.8 kWh before the car takes anything (our arithmetic). January is only a little better, at about 5.0 kWh. So through December and January, a Dunstable car’s charge comes almost entirely from the grid.
That is where the charger’s smart functions matter more than the panels. Every new home chargepoint sold in Great Britain has had to be smart since 30 June 2022, under the Electric Vehicles (Smart Charge Points) Regulations 2021, so it can schedule charging into cheaper overnight hours. A winter evening plug-in becomes an overnight charge without anyone setting an alarm.
The car has to be there
Solar can only go into a car that is parked and plugged in during daylight. If your car leaves early and returns at dusk, the summer surplus goes into a home battery, if you have one, or out to the grid. If the car is home at weekends, or you work shifts, more of it can go into the car. With a compatible setup, a charger can follow the surplus rather than draw whenever the car is plugged in. Our EV chargers page covers the EnSmart SmartBee-M we fit and what a compatible setup involves.
Which Dunstable homes can do this
Charging a car from your own roof needs two things: a roof you control and a parking space you can run a cable to. In the Dunstable built-up area, 34.0% of households live in semis and 14.7% in detached houses (Census 2021), and those are the homes where both usually come together. Terraces are 22.8%. Where a terrace has no drive, Central Bedfordshire Council’s pavement charging channel can carry a cable to the kerb, where the council agrees the address is suitable; it is a route for overnight charging more than for daytime solar, because the car has to be parked outside at the right time.
Flats, maisonettes and apartments are 28.4% of Dunstable’s households, a high share for the district. In a flat the roof is rarely yours to use, so solar for the car is not usually on the table, though a charger in an allocated bay may be. Our page on solar panels in Dunstable covers the roof side for houses.
Panels, charger and the paperwork
The VAT treatment differs. Under HMRC’s VAT Notice 708/6, residential solar panels are zero-rated until 31 March 2027, with 5% from 1 April 2027, while a home chargepoint installation is standard-rated at 20%. On a combined quote each should sit on its own line.
Grants differ too. The OZEV chargepoint grant covers renters and people who own and live in flats, with private off-street or allocated parking, at 75% of the cost up to £500 per socket; owner-occupiers of houses get no chargepoint grant. Our guide to who qualifies for the EV chargepoint grant sets out each case. Claims must be made through an OZEV-authorised installer; tell us your situation at the quote stage.
Central Dunstable sits in UK Power Networks’ Eastern Power Networks area, about 12.4 km from the nearest other network on NESO’s boundaries. The installer notifies UK Power Networks of the charger, and an array above 16 A per phase, 3.68 kW, needs a G99 approval before work starts. A 4 kW inverter, at 17.39 A, is just over that line, so allow for the approval in the timetable.
Sources: European Commission JRC, PVGIS 5.3 PVcalc (PVGIS-SARAH3, 2005–2023; 4 kWp, 35°, due south, 14% losses, building-mounted), run 15 October 2026; Ofgem, typical domestic consumption values from 1 July 2026; Electric Vehicles (Smart Charge Points) Regulations 2021; ONS, Towns and cities, characteristics of built-up areas: Census 2021, Table 5c (Dunstable BUA); Central Bedfordshire Council, Electric vehicle charging channels, read 19 October 2026; HMRC, VAT Notice 708/6; GOV.UK, Changes to electric vehicle chargepoint grant schemes from 1 April 2026 (updated 7 July 2026); UK Power Networks, Licence Boundaries open dataset; NESO, GIS Boundaries for GB DNO Licence Areas (May 2024); Energy Networks Association, EREC G98 Issue 2 (10 March 2025); EnSmart Power, SmartBee-M published specification. Daily averages, surpluses and charging times are our arithmetic.