Intelligent Octopus Go: the EV tariff that schedules your car

Intelligent Octopus Go gives you a long cheap overnight window in exchange for letting the supplier decide exactly when your car charges within it. You set the deadline and the state of charge you want; they schedule the power.

It is one of the cheapest ways to charge an electric car at home, the published rate as of August 2026 is 8p per kilowatt hour for up to six hours between 11:30pm and 5:30am, less than a third of the capped standard rate of 26.11p, and the trade-off is control and a dependency on three systems talking to each other.

What you get

A long off-peak window, up to six hours against the three or four of traditional overnight tariffs, at a rate that turns a typical EV into roughly 2p-a-mile motoring.

That rate applies to the whole house, not just the car. Anything running during the window is charged at the cheap rate: the dishwasher, the immersion heater, a home battery charging from the grid. At an 18p gap to the cap, every thousand household kilowatt hours moved into the window is worth about £180 a year on its own.

Charging outside the window at the cheap rate. If the supplier chooses to charge your car during the day because the grid is favourable, you are still billed at the off-peak rate for it. This is the part people miss and it is genuinely valuable: the smart scheduling can only ever work in your favour on price.

What you give up

Precise control. You set a departure time and a target charge. The supplier decides when within that period to draw power. If you need the car ready sooner, you override, and overriding usually means paying the standard rate for those units.

Simplicity. The car, or the charger, has to be supported and connected. Compatibility is specific: a particular car model, or a particular charger brand, is either supported or it is not.

Check compatibility before switching

This is the single biggest cause of disappointment.

The tariff works by the supplier issuing charging instructions. That requires either a supported vehicle, connected through its manufacturer’s account, or a supported charger. Not every combination works, and the list changes.

Confirm your specific car and charger are supported on the supplier’s current list before you switch, and be aware that a car that is supported directly may behave differently from one controlled through the charger. If neither is supported, the plain fixed-window version of the tariff still exists, at a less aggressive rate, and the four-line tariff arithmetic decides whether it still wins for your mileage.

When integrations break

They do, occasionally. A firmware update, an expired manufacturer account token, or a car that fell off the network overnight.

The failure mode is a car that did not charge, discovered in the morning, with the units that did flow billed at 26.11p instead of 8p. Worth knowing:

• Check the app shows a scheduled session before going to bed, at least for the first few weeks.
• Keep a manual override you know how to use.
• If a session is missed because the integration failed rather than because you unplugged, the supplier will generally credit the difference. Ask, with the session log open.

Whether it beats a plain overnight tariff

The comparison against a conventional fixed-window EV tariff comes down to three things:

Window length. A longer window means more household load caught at the cheap rate, not just the car, and six hours takes a battery, an immersion heater and a full dishwasher cycle comfortably.

The daytime rate. Compare it, because it applies to everything outside the window, which for most households is the larger volume, the trap the tariff calculation prices explicitly.

Whether you need control. Irregular schedules, or a car that must be ready at short notice, suit a fixed window you manage yourself.

For a household with a predictable overnight pattern and a supported car, the smart tariff usually wins on price. For an irregular one, the simpler tariff is often worth the slightly higher rate, paid as insurance against override charges.

With solar and a battery

The long cheap window makes grid-charging a home battery genuinely lucrative: 8p in, 26.11p avoided, roughly 14.7p of net gain per cycled unit after round trip losses, available all winter when the roof has little to offer.

The interaction to watch is that a cheap import rate reduces the value of self-consumption. If you can import at 8p overnight, a unit you generate and store during the day competes with an 8p alternative rather than a 26.11p one, and solar-charging the car can even price at a loss against exporting when a 12p export rate is on the table. It is still worth more to use daytime generation directly during the day than to export it, but the gap narrows everywhere the cheap window can reach.

That is not an argument against the tariff. It is a reason to model your solar savings using the tariff you will actually be on rather than the one you were on when you were quoted, which is exactly what the calculator’s tariff options exist for.

Do the arithmetic first

Take your annual mileage, your car’s efficiency, and your non-car consumption. Work out what the window would save on the car, what it would save on everything else you can move into it, and what the daytime rate costs on what remains. Rates change, so use the current published figures from the tariff page, and rerun the sum when they do: the whole calculation is four lines, and it is the difference between joining a tariff and joining a queue of surprised forum posts.