Home energy guide
EV tariff vs the price cap: when does it break even?
A smart EV tariff is cheap overnight but usually dearer than the cap during the day. Drive a normal mileage and the overnight savings almost always win comfortably.
Last updated:
Work out your own numbers with the tariff calculator →
An example (October–December 2026)
Picture a home using 2,700 kWh a year, plus an EV doing 8,000 miles. On a smart EV tariff it saves about £540 a year compared with the price cap.
Without the EV, the saving shrinks to about £62 a year, and it vanishes completely if the day rate is above about 30.9p. In short: the car is what makes these tariffs pay.
See the numbers
The EV does 3.5 miles per kWh, about 2,510 kWh at the plug including 10% charging losses.
| Tariff | Assumptions | Per year |
|---|---|---|
| Standard capped | 26.32p/kWh, 54.83p/day | ≈ £1,573 |
| Smart EV time-of-use | 6.5p night, 28p day (placeholder), 54.83p/day; 95% of EV and 20% of home use at night | ≈ £1,030 |
Cap: Ofgem, 1 Oct–31 Dec 2026. Night rate: Intelligent Octopus Go, from 6.5p (checked 31 Oct 2026). The day rate and standing charge are quoted per postcode, so 28p and 54.83p are placeholders: put your own quote into the calculator.
What tips the balance
- The day rate. Every 1p above the cap on daytime use costs about £22 a year (at 2,160 kWh of daytime home use).
- How much home use you can shift to night: dishwasher, washing machine, hot water, a home battery.
- Smart charging slots. Some tariffs bill extra cheap slots when the supplier controls charging. Even better.
- Exit fees. Leaving a fixed deal early can cost money. Intelligent Octopus Go's exit fee is £50, according to our earlier off-peak tariff guide.
The cap moves every quarter
Ofgem announces the January–March 2027 cap on 25 November 2026, so re-run the calculator then. The 0% VAT on home electricity runs from 1 October 2026 to 30 June 2027 (HMRC VAT Notice 701/19, checked 2 Nov 2026).
For running costs against petrol, see the EV cost comparison.
Sources (checked 27 October 2026 unless stated)
- Ofgem price cap, 1 Oct–31 Dec 2026 (published 26 Aug 2026; next announcement 25 Nov 2026)
- Octopus Energy: Intelligent Octopus Go: from 6.5p/kWh (checked 31 Oct 2026)
- Ofgem typical domestic consumption values — not re-checked today