Solar and EV charging in the UK — a 2026 guide

If you have an EV (or you're thinking about one), pairing it with solar is one of the strongest financial cases for going solar in the UK. The car is the biggest electricity load most households have, and a daytime-charging EV plus a south-facing roof can soak up most of a system's annual generation directly. This guide walks through how it works, when it pays back fastest, and what to size for.

The big picture

A typical UK EV uses around 2,500–4,000 kWh a year, depending on mileage and efficiency. That's similar to a household's entire non-EV electricity use. Two ways to power that:

• Charge from cheap overnight grid electricity (Octopus Go at ~9p/kWh, Cosy similar). Easy, predictable, no solar required.
• Charge from solar in the daytime. Free electricity (after the system is paid back), but only useful if the car is home and parked when the sun is generating.

For most UK homeowners with an EV, the right answer is both: charge from cheap-rate overnight as the default, top up from solar opportunistically during the day. Smart chargers automate this.

How solar EV charging actually works

The standard 7kW home charger ("Mode 3" / Type 2) is what's on most UK driveways. By itself, it pulls 7kW from wherever it can — house, grid, doesn't care. To get it to prioritise solar surplus, you need a smart charger that can read your generation meter.

Two popular options in the UK:

• MyEnergi Zappi. UK-designed, integrates directly with most solar inverters via current-clamp readings. Has an "Eco+" mode that only charges from solar surplus, and a "Smart" mode that mixes solar surplus with cheap-rate grid.
• Ohme Home Pro. App-driven, integrates with Octopus Go and a few other TOU tariffs. Automatically schedules charging to the cheap overnight window, and can also chase solar surplus.

Both cost £900–£1,500 installed in 2026. There are cheaper non-smart options around £400–£700, but they can't prioritise solar.

Sizing solar for an EV

A few rules of thumb:

• One full charge a week from solar: roughly 50 kWh of solar generation. Doable with a 4–5 kWp system, easily, even in mid-spring.
• All EV charging from solar: unrealistic in the UK — you'd need a 10+ kWp system and a daytime charging schedule, which most workers can't manage.
• Most realistic target: solar covers ~30–50% of EV charging across the year. The rest comes from cheap-rate overnight grid. Keeps the system size sensible.

If you're sizing solar specifically with EV in mind, lean towards a larger system (5–7 kWp instead of 3–4 kWp) — the marginal cost per kWp drops as you go up, and the extra summer surplus is genuinely useful for EV charging.

Time-of-use tariffs make the maths better

Pairing solar + EV with a time-of-use import tariff is the strongest financial case. The interaction:

• Cheap overnight slot — top the EV battery up to a useful daily floor.
• Solar daytime — opportunistic top-up beyond that floor.
• Peak hours (4–7pm) — avoid charging unless necessary; let the EV's existing charge cover evening trips.

The full pattern is in the Octopus Go and TOU tariffs guide.

Does adding an EV change how I size a battery?

Maybe. Two scenarios:

Scenario A: EV is home during the day

Lots of retired or work-from-home households fall into this category. Daytime solar surplus goes straight into the EV — no battery needed for that. A home battery is still useful for the evening electricity load (cooking, lighting, TV) but doesn't need to be huge.

Scenario B: EV is gone during the day, charges overnight

Most commuter households. Daytime solar surplus has nowhere to go in the EV — so a home battery captures it for evening use. Or you export to the grid. Or you wait until the weekend when the car is home.

In Scenario B, a battery actually pays for itself faster because there's a lot of unused daytime solar to capture. But the EV charging itself doesn't drive the battery sizing — the household evening load does.

Common mistakes

A few things to avoid:

• Buying a non-smart charger to "save money". A non-smart 7kW charger pulls 7kW regardless of solar generation. You'll pay grid rates while exporting solar at lower SEG rates. The chargeer's £400–£600 saving can vanish in two years of suboptimal charging.
• Sizing solar based on EV consumption alone. EVs are seasonal — summer trips are longer, winter trips often shorter. Sizing should be done with all your loads in mind, not just the car.
• Assuming you'll charge from solar all year. Winter solar generation is around 10–15% of annual output. December EV charging will mostly come from grid regardless of your setup. The financial case relies on the rest of the year.

What to ask when getting quotes

If you have an EV (or are about to), ask the installer:

• Can the proposed inverter integrate directly with my existing or planned EV charger? (Some can, via API or current-clamp.)
• Will the system be sized with EV charging in mind, or just for household load?
• Is the consumer unit big enough to add a 7kW EV charger circuit if I don't have one yet?

A reputable installer will treat solar + EV as one combined system rather than two separate purchases.

Related

• Solar with Octopus Go and time-of-use tariffs in 2026
• Solar battery storage UK — worth it in 2026?
• Are solar panels worth it in the UK in 2026?
• Use the savings calculator