EV and heat pump: Intelligent Octopus Go or Cosy Octopus?
One import tariff, two big electric loads: how Cosy's three cheap periods compare with Intelligent Octopus Go's cheap night, and how to decide.
Tariff facts, checked 28 October 2026
| Cosy Octopus | Heat pump tariff |
|---|---|
| Cheap rate | Three cheap periods: 04:00 to 07:00, 13:00 to 16:00 and 22:00 to 00:00 |
| Times | Peak rate 16:00 to 19:00 |
| You need | A heat pump, electric radiators or an electric boiler |
| Intelligent Octopus Go | EV tariff with smart charging |
| Cheap rate | From 7.9p/kWh (Octopus's advertised smart charging rate) |
| Times | 23:30 to 05:30 for the whole home, plus up to 6 hours of scheduled car charging in any 24 hours |
| You need | A compatible car or charger, a smart meter sending half-hourly readings and the Octopus app |
Quick answers
- Cosy Octopus gives eight cheap hours a day in three periods: 04:00 to 07:00, 13:00 to 16:00 and 22:00 to 00:00.
- Cosy has a peak rate from 16:00 to 19:00, which Octopus sets 50% above your region's day rate.
- Intelligent Octopus Go has a lower cheap rate for car charging and six cheap hours a night for the home.
- Octopus says Intelligent Octopus Go usually makes more sense with an EV and a heat pump, depending on how much you drive.
A heat pump and an electric car are the two biggest electric loads a home can have. You can only have one import tariff, so the question is which Octopus tariff fits both.
Cosy Octopus
Cosy is built for heat pumps. It has three rates:
- Cosy hours, eight a day: 04:00 to 07:00, 13:00 to 16:00 and 22:00 to 00:00. Octopus sets these at 51% below your region’s day rate.
- Peak, 16:00 to 19:00, at 50% above the day rate.
- Day rate at all other times.
The spread-out cheap periods suit heat pumps, which work best running steadily and topping up through the day.
Intelligent Octopus Go
Intelligent Octopus Go has a lower cheap rate than Cosy’s cosy hours, for six hours every night (23:30 to 05:30) for the whole home, plus up to six hours of scheduled car charging. Your heat pump can use those hours to pre-heat the house and heat the hot water cylinder.
Which usually wins
Octopus says it usually makes more sense to choose Intelligent Octopus Go rather than Cosy if you have both an EV and a heat pump, depending on how much you drive. The car is the reason: thousands of kilowatt-hours a year at Intelligent Octopus Go’s low rate usually outweigh the benefit of Cosy’s afternoon cheap period for heating.
Cosy can come out ahead for:
- low-mileage drivers, where the car is a small share of use,
- large heating loads in homes that cannot store heat overnight,
- homes where a lot of heating has to run in the afternoon.
Getting the most from Intelligent Octopus Go with a heat pump
- Heat your hot water cylinder in the night window.
- If your home holds heat well, raise the target temperature slightly overnight and let it drift down in the day.
- Avoid boosting heating in the evening, when you pay the day rate.
How to decide
Add up your annual heating kWh (from your heat pump’s app or installer’s estimate) and your car’s annual kWh, then get quotes for both tariffs for your postcode. If the car is the larger load, Intelligent Octopus Go is very likely to win.
How we test and where our numbers come from
Tariff times, rules and rates come from Octopus Energy's own tariff pages and its public price API on the date shown. Off-peak rates quoted are national; day rates and standing charges vary by region, so check your postcode. EV Compared earns a referral reward if you switch through our Octopus links; it does not change what we write. Last checked 28 October 2026. How we work out our own figures.
Frequently asked questions
Can my heat pump use Intelligent Octopus Go's cheap hours?
Yes. Everything in your home gets the cheap rate from 23:30 to 05:30, and during any extra slots when Octopus schedules your car. A heat pump can pre-heat the house and hot water in those hours.
Who should choose Cosy over Intelligent Octopus Go?
Low-mileage drivers with a large heating load, especially in older or less insulated homes that need heat through the day. Cosy's afternoon cheap period helps there.
Do I need a heat pump for Cosy?
Octopus says you need a heat pump, electric radiators or an electric boiler, though it need not have been installed by Octopus.
Sources and further reading
- octopus.energyOctopus Energy: Cosy OctopusThree cosy periods; 51% below day rate; peak 16:00 to 19:00 50% above; eligibility; fixed and flexible versions; checked 28 October 2026
- api.octopus.energyOctopus price API: Cosy OctopusRate bands on 28 October 2026
- octopus.energyOctopus Energy: EV tariff FAQsUsually more sense to choose Intelligent Octopus Go rather than Cosy with an EV and a heat pump
EV Compared
The EV Compared editorial team tracks the UK electric vehicle market full time: new model launches, list prices, WLTP and real-world range, public charging tariffs and the tax rules that decide what an EV actually costs to run. Every guide is checked against manufacturer specifications and official GOV.UK figures, and updated whenever the numbers move.
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