A car battery and a home battery are not in the same size class, and that one fact settles most of the questions Luton drivers bring to us about storage. The Energy Saving Trust says a typical home battery might be 10 kWh. A 60 kWh car battery, a size we use here as an example, holds six times that on our arithmetic. So a home battery is never sized to fill the car, and a quote built that way deserves a second look. Our Luton EV charger installation page covers the charger itself; this guide is about where a battery fits around it.
The question is spreading. DVLA records about 4,251 privately kept plug-in vehicles across Luton borough at the end of June 2026, up from 2,910 a year earlier: about 1,341 more, a rise of about 46% on our arithmetic. Those are vehicles across the whole borough, not households with a charger, but each new one raises the same question about the house.
Two batteries, two jobs
The car’s battery is a store for driving. The home battery is a store for the house, and its natural job is moving electricity from one part of the day to another: daytime solar into the evening, or cheaper overnight electricity into the teatime peak.
Run the numbers the other way and the mismatch is plain. At 7 kW, a charger takes about 7 kWh an hour, so it would empty a 10 kWh home battery in about an hour and a half (our arithmetic). The car would gain a fraction of a full charge, and the house would then buy its evening electricity from the grid. In most homes it is simpler to let the car charge overnight from the grid and leave the battery for the house.
What sizes a battery instead
The Energy Saving Trust says there is no exact formula for working out what size of battery you need. What it depends on is your own consumption. Ofgem’s typical domestic consumption value is 2,500 kWh a year, about 6.8 kWh a day on our arithmetic, and only part of that falls in the evening. A battery is sized to cover that evening share, with room for the tariff you are on and the panels you have, if any.
On cost, the Energy Saving Trust puts a home battery between £1,500 and £10,000, with a 5 kWh system at around £4,600, and gives a typical lifespan of about 10 to 12 years. Those are national figures, not our prices; a real number comes from a survey.
Where solar changes the picture
Panels give a battery something to store. PVGIS 5.3 puts a 4 kWp south-facing array in Luton at about 479 kWh in June, roughly 16 kWh a day, and about 135 kWh in December, roughly 4.4 kWh a day (our arithmetic). On a June day there is often more than the house uses, and with a compatible setup the surplus can go into the car if it is parked at home, or into a battery for the evening if it is not. In December the roof makes less than the house needs, so the car charges overnight from the grid and a battery, if you have one, mostly stores cheaper overnight electricity. Our page on battery storage in Luton covers sizing in more detail.
The supply both of them share
A 7 kW charger draws 32 A continuously, and domestic main fuses are commonly 60 A, 80 A or 100 A. Add a battery that discharges into the house at the same time and the survey has to look at the whole supply, not each item on its own. Load management, a current sensor on the incoming supply, lets the charger take only the headroom that is spare. Central Luton sits in UK Power Networks’ Eastern Power Networks licence area, about 18.6 km from the nearest other network on NESO’s boundaries. UK Power Networks says it can upgrade a main fuse from 30 or 60 A to 80 or 100 A where needed.
The paperwork differs for each piece. The installer notifies UK Power Networks of a new chargepoint, and our guide to EV charger installation cost shows where load management and any supply work appear on a quote. A battery or solar system up to and including 16 A per phase, 3.68 kW, is notified under G98 before commissioning or within 28 days after; anything larger needs a G99 approval before work starts, and UK Power Networks says it automatically approves applications whose maximum export is under 5 kW.
VAT and grants treat them differently
HMRC’s VAT Notice 708/6 zero-rates a residential battery until 31 March 2027, with 5% from 1 April 2027, but a home chargepoint is standard-rated at 20%. On a combined quote, each should sit on its own line. The OZEV chargepoint grant helps renters and flat owner-occupiers with private off-street or allocated parking, at 75% of the cost up to £500 per socket; it does not cover batteries, and owner-occupiers of houses get no chargepoint grant. Our guide to who qualifies for the EV chargepoint grant has the detail. Claims must be made through an OZEV-authorised installer; tell us your situation at the quote stage.
What a battery will not do
A standard grid-tied battery shuts down in a power cut, so neither the house nor the charger runs from it during an outage unless backup was designed in, with extra equipment, at extra cost. It will not make a Luton home self-sufficient in winter either, with December output at roughly 4.4 kWh a day from the array above.
Which Luton homes this applies to
The pairing is simplest in a house with a drive. At the 2021 Census, 40.3% of Luton’s 78,942 households lived in a semi and 12.9% in a detached house. In the 20.5% in purpose-built flats, a battery and a charger both need the freeholder’s written consent, and for the 29.0% who rent privately the landlord decides. Where a battery would physically go in each house type is covered in our guide to where a battery goes in Luton’s semis, terraces and flats.
Sources: Energy Saving Trust, Battery storage (last updated 19 August 2026); Ofgem, typical domestic consumption values from 1 July 2026; DfT and DVLA, VEH0142 licensed plug-in vehicles by keepership and local authority, Luton, end of June 2025 and 2026 (published 23 September 2026); European Commission JRC, PVGIS 5.3 (PVGIS-SARAH3 2005–2023; 4 kWp, 35°, due south, 14% losses; run 15 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, fuse upgrade guidance and Solar panels and energy storage: cost, time and what’s involved; NESO, GIS Boundaries for GB DNO Licence Areas (May 2024); Energy Networks Association, EREC G98 Issue 2 (10 March 2025); ONS Census 2021, TS044 and TS054 via Nomis (Luton E06000032). Ratios, per-day figures and changes are our arithmetic.