A common assumption among N10 drivers is that a car on the drive calls for a bigger home battery. The arithmetic says otherwise. A battery sized for a Muswell Hill household’s evenings is small next to what a car takes, and trying to stretch it to fill the car usually means paying for capacity that sits idle for much of the year.
This guide sets out why the battery is sized to the house, what an Edwardian Muswell Hill roof leaves over for the car, and how the two share one supply. For the charger itself, see our guide to fitting an EV charger in Muswell Hill.
The car and the house are different sizes
The Energy Saving Trust says a typical home battery system might be 10 kWh, and that there is no exact formula for working out what you need. Set that beside a car: a 60 kWh charge is six times the Trust’s typical battery, on our arithmetic. Set it beside the house instead: Ofgem’s typical domestic consumption value from 1 July 2026 is 2,500 kWh a year, about 6.8 kWh a day. A battery in the 5 to 10 kWh range is the size of a household’s day, not a car’s week. In Muswell Hill, where 55.4% of ward households own their home (Census 2021), that is a decision many owners can take for themselves.
What a Muswell Hill roof leaves over
PVGIS puts an unshaded 4 kWp south-facing array in Muswell Hill at about 475 kWh in June and 142 kWh in December. On our arithmetic, an average June day makes about 15.8 kWh, roughly 9 kWh above a typical day’s use, and that surplus is what a compatible setup can divert to a car at home in daylight. An average December day makes about 4.6 kWh, less than the house uses, so there is nothing left for the car or the battery. Dormers and chimney stacks on the suburb’s houses, mostly built between 1896 and 1913, will reduce both figures, and Muswell Hill and Fortis Green have been conservation areas since 1 March 1974, which can affect where panels go.
So what is the battery for?
On an N10 roof in June, a battery takes what the house and car have not used and carries it into the evening. On a December day, its value comes from the tariff: charging from cheap overnight units and running the house through the expensive hours. Neither job needs a battery the size of a car. The Energy Saving Trust puts a 5 kWh system at around £4,600, within a range of £1,500 to £10,000, with a typical lifespan of about 10 to 12 years, and says fitting storage at the same time as panels costs less than a separate visit later. The battery systems in our own job photos are EnSmart.
Charging both from one N10 supply
If both the car and the battery fill overnight, they share one supply in the same hours. A 7 kW charger draws 32 A continuously, and domestic main fuses are commonly 60 A, 80 A or 100 A, so in a Fortis Green semi running a battery charge, a car charge and a late electric shower together, load management matters. A current sensor on the incoming supply lets the charger take only the headroom that is spare. Every new home chargepoint has had to be smart since 30 June 2022, so the car’s window can be set to sit alongside the battery’s. Muswell Hill’s town centre is in UK Power Networks’ Eastern Power Networks licence area, and the installer notifies UKPN of both the charger and the battery.
Haringey’s plug-in trend
DVLA records 4,127 privately kept plug-in vehicles across Haringey at the end of June 2026, up from 3,531 a year earlier: 596 more, about 17% on our arithmetic. We use the privately kept figure because company registrations sit at a fleet’s address. The count covers the whole borough, Wood Green and Tottenham included, and it counts cars rather than chargers, and ownership runs higher here than across the borough: 59.2% of Fortis Green households own their home, against 37.2% across Haringey (Census 2021), so more N10 households can decide on a charger and a battery for themselves.
Converted houses and the battery’s home
Muswell Hill ward’s largest housing group, 32.6% of households, lives in part of a converted or shared house. In a split Edwardian house, a battery and a charger both need to sit on the flat’s own supply, and the lease decides where equipment can go. Our guide to Muswell Hill’s conservation areas and adding a battery covers indoor siting in those houses. Flat owners and renters with a private or allocated space can claim 75% of a chargepoint’s cost, up to £500 per socket; our guide to who qualifies for the EV chargepoint grant explains, and claims must be made through an OZEV-authorised installer.
VAT, and one plain caveat
The two devices are taxed differently, so an N10 quote that fits both at once should show them on separate lines. A residential battery installation carries 0% VAT until 31 March 2027, then 5%; a home EV charger is standard-rated at 20%. And a standard grid-tied battery shuts down in a power cut unless backup has been designed in and priced as its own line. For sizing storage to your own bills, see our page on battery storage in Muswell Hill; for the charger range and speeds, our home EV charger guide.
Sources: Energy Saving Trust, Battery storage (updated 19 August 2026); Ofgem, typical domestic consumption values from 1 July 2026; European Commission JRC, PVGIS 5.3 (PVGIS-SARAH3 2005–2023; 4 kWp, 35°, due south, 14% losses; Muswell Hill run 15 October 2026); London Borough of Haringey, conservation-area appraisal and list of conservation areas; DfT and DVLA, VEH0142 licensed plug-in vehicles by local authority, Haringey, 2026 Q2 and 2025 Q2 (published 23 September 2026); ONS Census 2021, TS044 and TS054, Muswell Hill (E05013594) and Fortis Green (E05013589) wards and Haringey (E09000014), via Nomis; HMRC, VAT Notice 708/6; UK Power Networks EV and fuse guidance and licence boundaries open data; Electric Vehicles (Smart Charge Points) Regulations 2021; GOV.UK, Changes to electric vehicle chargepoint grant schemes from 1 April 2026 (updated 7 July 2026). Daily, ratio and percentage figures are our arithmetic.