Is It Cheaper to Charge EVs From Solar? Cost per Mile in 2026

Yes — by a wide margin, but not for the reason usually given. Solar electricity is cheap because the panels are cheap per kilowatt-hour over their life, not because sunshine is free, and once an array is built the true cost of putting its output into a vehicle is the export payment you give up. This article puts the four ways a business can buy vehicle electricity side by side, in pence per mile, using published 2026 prices.

The four prices

• Public rapid and ultra-rapid chargers (50 kW+): 77p/kWh, the August 2026 pay-as-you-go average in the Zapmap Price Index.
• Public standard chargers (3–49 kW): 54p/kWh, same source.
• Your own site, from the grid: 24.14p/kWh, the average non-domestic price including Climate Change Levy in the first quarter of 2026 (DESNZ Quarterly Energy Prices, table 3.4.2). Your own bill's unit rate is the better number to use.
• Your own site, from solar: about 5.4p/kWh in London to 6.4p/kWh in Glasgow, on our arithmetic: the DESNZ 2025/26 average installed cost for non-domestic 10–50 kW systems (£1,167 per kW), divided by 25 years of PVGIS-modelled output at a 10° roof pitch with 0.5% a year degradation. Capital only — no finance or maintenance.

Pence per mile

Zapmap converts its prices into about 16p and 23p per mile for an average-efficiency electric car, which implies roughly 3.4 miles per kWh. Vans use more energy per mile; 2.5 miles per kWh is used below as an illustration, not a published figure — use your own vehicles' consumption.

The first step — getting vehicles off public networks and onto the site's own supply — is worth more than the second. Moving 10,000 car miles from public standard chargers to grid-fed workplace charging saves about £880; moving the same miles from the grid to solar saves another £520–£550. Both are real; the order matters when budget is limited.

The export trap in "free" solar charging

Once the array exists, its capital cost is sunk. The question for each kilowatt-hour is then whether it is worth more in a vehicle or exported. If the site's export tariff pays, say, 5p/kWh, a solar kWh diverted into a car costs 5p of lost export — about 1.5p a mile — and saves a grid kWh at 24p. That is the real, marginal saving, and it is still large. A model that values solar charging at zero overstates it; one that values it at the export rate gets it right.

Why your numbers will differ

• Timing. Solar charging only happens when vehicles are parked in daylight. Staff cars parked nine to five can absorb a lot of midday output; vans out all day cannot.
• Season. In London a well-angled array generates about three times as much in June as in December, so the solar share of charging falls sharply in winter.
• Your tariff. Standing charges, capacity charges and time-of-use rates mean the unit you save is not always the average unit you pay.
• Charger control. Without a meter reading at the supply intake, chargers cannot tell when there is surplus to follow — how charging from solar works in practice explains the set-up.

What to do with this

Count your vehicles' kilowatt-hours by source for a month: public, site grid, site solar. The pence-per-mile gaps above turn that into a money figure quickly, and they show where commercial solar EV charging earns its keep on your site — usually on long-dwell daytime parking. The full business case turns the same prices into a full model with grants and tax relief, and what a solar EV charging system costs covers the capital side.

Sources

• Zapmap Price Index, August 2026 — zapmap.com.
• DESNZ Quarterly Energy Prices, table 3.4.2, Q1 2026.
• DESNZ Solar PV cost data 2025/26 (published 28 May 2026).
• EU JRC PVGIS 5.3; Jordan & Kurtz (2013) on degradation, doi.org/10.1002/pip.1182.