There is no single best Octopus tariff for a battery. The time-of-use tariffs that suit batteries have entry rules, so the real question is which tariffs you can join, and which of those gives the biggest gain over the best tariff you could have without a battery.
This guide sets out the time windows (checked on Octopus’s pages and terms in October 2026), the rules for joining each tariff, and Fortyeight’s modelled results for four types of home. To see the result for your own home, run it on your own meter data.
Time windows and rates side by side
Rates are Octopus’s published London (region C) prices on 25 October 2026, shown on a 5% VAT basis. Household electricity in Great Britain is zero-rated for VAT from 1 October 2026 to 31 March 2027, so bills paid now are about 4.8% lower. Regional rates differ slightly.
| Tariff | Cheap window (UK time) | Cheap rate | Other rates | Who can join |
|---|---|---|---|---|
| Agile Octopus | Changes every half-hour | Averaged 16.5p, 02:00–05:00 | Averaged 35.7p, 16:00–19:00; capped at 100p | Any smart-meter home |
| Intelligent Octopus Go | 23:30–05:30 | 6.93p | 37.93p | Electric car or plug-in hybrid, compatible car or charger |
| Octopus Go | 00:30–05:30 | 9.87p | 36.26p | Electric car charged at home |
| Cosy Octopus | 04:00–07:00, 13:00–16:00, 22:00–00:00 | 14.83p | 45.35p, 16:00–19:00; 30.24p otherwise | Heat pump, electric radiators or electric boiler |
| Octopus Flux | 02:00–05:00 | 16.97p | 39.25p, 16:00–19:00; 28.11p otherwise | Solar, home battery, MCS certificate; Octopus import and export |
| Flexible Octopus | None | 27.93p flat | — | Anyone |
Flux export pays 4.72p from 02:00 to 05:00, 30.31p from 16:00 to 19:00 and 11.11p otherwise in London. Outgoing Octopus pays a flat 12p, but only for eligible generation such as MCS solar.
Every one of these smart tariffs needs a smart meter that Octopus can read: SMETS2, or a SMETS1 meter made by Secure, according to its tariff pages.
The entry rules that decide your shortlist
- Octopus Go requires an electric car that you charge at home. It doesn’t require a home charger.
- Intelligent Octopus Go requires an electric car or plug-in hybrid (clause 2.3.1.3 of the smart tariff terms) and a car or charger Octopus can control. It gives up to six hours of cheap electricity for the whole home between 23:30 and 05:30. A battery with no car does not qualify.
- Cosy Octopus requires a heat pump, electric radiators or an electric boiler.
- Octopus Flux requires solar panels, a home battery and a copy of your MCS certificate, with both your import and export supply with Octopus.
- Agile Octopus only requires a suitable smart meter.
Octopus also sells Charge Pack, which controls compatible batteries (it lists GivEnergy, Fox and AlphaESS among others, with Tesla “coming soon”) alongside Intelligent Octopus Go, Go, Flexible or Fixed tariffs plus Outgoing. It manages the battery for you. It does not make you eligible for Go or Intelligent Octopus Go. Intelligent Octopus Flux, which needs solar and an approved battery, was shown as unavailable or limited to Octopus-installed systems when we checked, so it is not in the model.
Which tariff wins, by type of home
The figures show what a 10 kWh battery adds each year over the best tariff the same home could join without a battery. That is the honest number; comparing with your current bill also counts the saving from switching tariff.
| Modelled household | Agile | Intelligent Octopus Go | Octopus Go | Cosy | Flux |
|---|---|---|---|---|---|
| Typical, 2,500 kWh (London) | £210 | not eligible | not eligible | not eligible | not eligible |
| Typical (North Scotland) | £241 | not eligible | not eligible | not eligible | not eligible |
| EV, 2,700 kWh + 2,000 kWh charging (London) | £254 | £541 | £393 | not eligible | not eligible |
| EV (North Scotland) | £244 | £702 | £554 | not eligible | not eligible |
| Heat pump, 2,700 + 3,500 kWh (London) | £384 | not eligible | not eligible | £209 | not eligible |
| Heat pump (North Scotland) | £436 | not eligible | not eligible | £499 | not eligible |
| 4 kWp MCS solar, 3,500 kWh (London) | £229 | not eligible | not eligible | not eligible | £448 |
| 4 kWp MCS solar (North Scotland) | £278 | not eligible | not eligible | not eligible | £542 |
For the solar homes, Agile is paired with Outgoing Octopus. Every figure assumes 95% usable capacity, 90% round-trip efficiency and a 5 kW inverter.
Some patterns stand out.
EV homes should look at Intelligent Octopus Go first. Its 31p gap between night and day is the widest of any tariff here, and the six-hour window easily refills 10 kWh. The model only counts the fixed 23:30–05:30 window, not any extra smart-charging slots Octopus gives the car.
Agile wins when nothing else is available, and sometimes even when it is. For the London heat-pump home, Agile without a battery was already cheaper (£1,458 a year) than Cosy without one (£1,902). So Agile plus a battery came first. In North Scotland the gap was far smaller (Agile £1,787 against Cosy £1,935, as Agile prices there averaged 24.9p against 20.7p in London), and Cosy plus a battery came out ahead.
Flux is the one place where a bigger battery keeps paying. Because Flux pays for exports from the battery at the 16:00–19:00 peak, a 13.5 kWh battery added £594 a year in London against £448 for 10 kWh. On every other tariff, sizes above 10 kWh added little for these homes.
Agile: what the last 12 months looked like
Agile prices follow the wholesale market. Octopus updates them between 16:00 and 20:00 each day for the next 24 hours, and Price Cap Protect stops them going above 100p/kWh. Over the 12 months from 25 October 2025 to 24 October 2026, London’s Agile import price (5% VAT basis):
- averaged 20.7p/kWh
- averaged 35.7p from 16:00 to 19:00, 16.5p from 02:00 to 05:00 and 15.7p from 13:00 to 16:00
- went below zero in 487 of 17,520 half-hours, so you were paid to use electricity
- peaked at 86.7p
North Scotland averaged 24.9p, with a 16:00–19:00 average of 40.7p. The regional Agile pages show every area.
One past year will not repeat. Agile’s spread between cheap and expensive hours depends on gas prices, wind output and demand, and it changes from year to year. Treat a battery’s Agile saving as an estimate with a wide margin. The fixed-rate tariffs in this guide (Go, Intelligent Octopus Go, Cosy, Flux) are easier to model, but their rates can change too: the figures here are the ones published on 25 October 2026.
Exports: who pays for battery power
This is the most common misunderstanding. Under Octopus’s export terms (version 2.2, 1 November 2024), Outgoing and Agile Outgoing pay only for power from eligible generation such as MCS solar. Clause 4.5.1(i) excludes payment for exports “not generated by an eligible generation asset, including… batteries”. A battery that charges cheaply overnight and exports at teatime earns nothing on those tariffs.
Flux works differently. It is designed for solar-plus-battery homes and pays its export rate for battery exports. If you have MCS solar and are adding a battery, Flux belongs on your shortlist. See export tariffs explained for the details.
How to choose
- List what you own: an EV, a heat pump, MCS solar. That gives you your eligible tariffs.
- Download a year of half-hourly data. Our guide to downloading smart meter data shows how.
- Price that data on every eligible tariff with no battery, and note the cheapest.
- Add the battery to each eligible tariff and compare with that cheapest no-battery bill.
- Check the battery’s controller can follow the tariff you pick; Agile needs one that can follow half-hourly prices.
If you have no EV, heat pump or solar, the guide to batteries without solar explains why Agile is your only battery-friendly choice, and what a standalone battery can earn. To check whether any of these savings justify a quote, see whether home batteries are worth it.
This is a model, not financial advice. Check the tariff’s current terms with Octopus before switching. Fortyeight is independent and not affiliated with Octopus Energy.