Solar + EV: the cheapest miles you'll ever drive.

Last updated: 15 July 2026 · Written by the ECONEXIS team, MCS-accredited installers.

An electric car does roughly 3.5–4 miles per kWh. A typical solar system we design generates 4,000–6,000 kWh a year. On paper, that's 14,000–24,000 miles of driving from your roof — more than most people drive. The catch, and the fix, are what this guide is about.

The honest catch: timing

Your panels peak at midday; your car is often at work with you. Plug in on a Saturday and yes — the car drinks sunshine directly. On weekdays, unmanaged, your solar exports for pennies while your car later charges on evening-rate power. Two pieces of kit close that gap.

Fix 1: a solar-aware charger

A smart EV charger with a solar mode watches what your roof is producing and diverts only the surplus into the car — so whenever the car is home in daylight, it soaks up power you'd otherwise export. Charging speed floats with the sunshine. It's the single best upgrade for anyone home in the day, working hybrid, or running two cars.

Fix 2: a battery + a smart tariff

A home battery time-shifts your solar into the evening — and it unlocks the EV tariffs that make this really work. Off-peak overnight rates for EV owners run at roughly half the standard rate or better: the car fills up cheap at 3am, the house battery can top up cheap too, and the roof carries the daytime. Between sunshine and off-peak, many of our solar+battery+EV customers barely buy peak-rate electricity at all. (Battery costs here.)

What the miles cost

• Petrol — a typical car costs ~12–16p per mile in fuel.
• EV on standard-rate electricity — roughly 6–8p per mile.
• EV on an off-peak overnight tariff — roughly 2–3p per mile.
• EV on your own solar surplus — effectively the export you gave up: ~1–2p per mile.

That last line is why solar and EVs belong together: 8,000 miles a year on sunshine and off-peak instead of petrol is £1,000+ a year staying in your pocket, before the house's own savings.

Designing it as one system

The order matters: tell us you have (or plan) an EV and we size the array bigger, spec the inverter for the battery, and position the charger properly — rather than bolting parts together later. One design, one install, one set of paperwork. Get a free custom design — usually back within 24 hours, anywhere across Bedfordshire, Hertfordshire, Buckinghamshire, Essex & Kent.

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