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 calculator tests both steps on your own vehicles.

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. Whether the solar step pays at all depends on parking hours — see the break-even test.

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.