EV tariffs explained: the off-peak window that changes the maths
A standard tariff charges one rate all day — 26.11p/kWh at the July 2026 Ofgem price cap. EV tariffs instead give you a few cheap overnight hours (currently 8.0p/kWh on the cheapest we track) in exchange for a slightly higher day rate. If you can charge in the window, the saving is dramatic; if you cannot, the higher day rate costs you. This page shows both sides.
Prices based on the Ofgem price cap of 26.11 p/kWh, effective 1 July 2026.Source: Ofgem
Live rates: the same charge on each tariff
| Tariff | Unit rate | Full charge, average EV (62 kWh) | Pence per mile (average EV) |
|---|---|---|---|
| Ofgem price cap | 26.11p/kWh | £18.54 | 6.4p |
| Octopus Go 12M Fixed off-peak (London example) | 9.50p/kWh | £6.75 | 2.3p |
| Intelligent Octopus Go 12M Fixed off-peak (London example) | 8.00p/kWh | £5.68 | 2.0p |
Octopus rates fetched live from their public API (London region example; rates vary by region — see costs by region). “Average EV” is the mean of the 23 models we track, losses included. Off-peak figures assume all charging happens inside the cheap window.
How the window actually works
A few hours, usually after midnight
Go-style tariffs publish a fixed overnight window of around five hours. You schedule the car (or the charger) to draw power only then. A 7 kW wallbox can add roughly 35 kWh inside a five-hour window — most of most batteries.
“Intelligent” tariffs flex the window
Smart variants control your charging session themselves and can extend cheap hours beyond the advertised window when the grid is quiet — usually the cheapest option of all if your car or charger is compatible.
The day rate is the catch
EV tariffs typically price daytime electricity above the price cap level — for the whole house, not just the car. Heavy daytime users with modest mileage can end up worse off. The break-even depends on your mileage and daytime consumption; our calculator lets you test your own numbers.
Three-pin owners rarely benefit fully
At 2.3 kW, a five-hour window only adds ~11 kWh. If you rely on a three-pin plug, you may not fit a useful charge inside the cheap hours — see the three-pin guide.
10,000 miles on the price cap
£644.40
average EV, home charging
Same miles, cheapest off-peak window
£197.44
if every charge fits the window