The best tariff for solar and a battery: which suits your home

No single tariff suits every home with solar panels and a battery. The deciding question is what else you run on electricity. We checked Octopus's tariffs only, the ones our calculator models; other suppliers sell time-of-use and electric car tariffs that we haven't compared here. When we checked on 24 September 2026:

• With an electric car: Intelligent Octopus Go 12M Fixed charged 8p per kWh from 23:30 to 05:30 in every region, and 35.48p at other times in London (without VAT). It needs a compatible car or charger and Octopus as your supplier. In our example of a car-owning home with a battery and Outgoing Octopus's 12p export, it beat a single-rate tariff by about £173 a year.
• Without a car: Octopus Flux, for homes with solar and a battery, buys and sells at three times of day, with a 28.60p export rate from 4pm to 7pm in London. It needs your import and export with Octopus. In our example without a car, at September 2026 prices, it beat a single-rate tariff with 12p export (needs Octopus as your electricity supplier) by about £15 a year.
• With a heat pump: Cosy Octopus has three cheap periods a day. It needs a heat pump, electric boiler or electric radiators.
• If you automate everything: Agile Octopus changes price every half hour.

Intelligent Octopus Flux, which runs your battery for you, was closed to new customers except those who bought solar and a battery from Octopus. Every saving on this page is "with this tariff": it only applies if you meet the tariff's condition.

Tariffs open to new customers

These are Octopus's rates for London on 24 September 2026, without VAT. There is no VAT on household electricity in Great Britain from 1 October 2026 to 31 March 2027. Rates vary by region.

For comparison, the Ofgem price cap for a single-rate tariff paid by Direct Debit is 26.32p per kWh from 1 October to 31 December 2026, a Great Britain average. On Intelligent Octopus Go the whole home gets the 8p rate from 23:30 to 05:30, and when Octopus schedules extra car charging outside that window, the home gets the cheap rate then too. A battery can charge in those hours, but a battery alone does not qualify you: you need the car or charger. Octopus was selling Intelligent Octopus Go and Octopus Go only as 12-month fixes; its variable Intelligent Octopus Go closed to new customers on 17 February 2026.

Full details are in our guides to Octopus Flux, Intelligent Octopus Flux and Outgoing Octopus, including which import and export tariffs can be combined.

Why the right tariff depends on your usage

A battery saves money in two ways: it stores daytime solar for the evening, and on a time-of-use tariff it can fill up from the grid when electricity is cheap. For a home using around 2,500 kWh a year, the first matters most, and cheap overnight charging adds little, as our solar battery guide shows. Homes that use much more, because of an electric car or a heat pump, run out of solar and stored energy long before the day ends. That is where a cheap-rate window and a battery to carry it into the day pay off.

The price per kWh a battery can capture shows the difference. Assuming the battery returns 90% of what goes in, 1 kWh bought at the cheap rate and used later saves:

On a single-rate tariff, grid charging gains nothing: 1 kWh bought at 26.32p returns 0.9 kWh, worth 23.69p.

Worked example: a home with an electric car

These figures come from our calculator's reference cases, at today's prices. They are estimates, not a quote.

• Home: Birmingham, 4,500 kWh a year including an electric car, out for part of the day.
• System: 6 kWp of panels and a 10 kWh battery (5 kW, 90% round trip), £13,500 installed in our calculator's price model; panels alone £9,300.
• Tariffs: the 26.32p single-rate price cap rate for October to December 2026, or Intelligent Octopus Go 12M Fixed at its London example rates (8p from 23:30 to 05:30, 35.48p otherwise), both with Outgoing Octopus's 12p export (needs Octopus as your supplier). On Intelligent Octopus Go, the battery also charges from the grid overnight, about 624 kWh a year.

With the battery, Intelligent Octopus Go leaves this home about £173 a year better off than the single-rate tariff (£1.89 + £171). With panels alone, it comes out about £92 a year worse in our model (£421 − £329.20), because every kWh used outside the cheap window costs 35.48p. Our model counts the car's charging as ordinary night-time use from 22:00 to 06:00, not smart charging timed to the cheapest hours, so a car smart-charged in the cheapest hours would put more of its use on the cheap rate than this estimate assumes. The battery is what makes the dear day rate affordable: it carries 8p electricity into the day.

The calculator's headline measures each tariff against the same tariff without panels or battery. On that basis the system saves about £1,542 in the first year with Intelligent Octopus Go (payback about 9 years) and £1,183 on the single-rate tariff (about 12 years). Part of that difference only exists because the Intelligent Octopus Go bill without solar is higher: £1,371 in our model, against £1,184.40 on the single-rate tariff (4,500 kWh × 26.32p). The net costs in the table are the fairer comparison. If you keep your supplier and export at an open-to-all 6p, the Intelligent Octopus Go saving falls to about £1,407. Standing charges aren't included; in London, Intelligent Octopus Go's was 42.29p a day, and the price cap's for October to December is 54.83p, a Great Britain average.

Worked example: a battery home without a car

A Manchester home using 3,600 kWh a year, with 5 kWp of panels and a 5 kWh battery (£11,300), can't join the car tariffs. We run this case at September 2026 prices including 5% VAT, because Flux's rates and the price cap both change on 1 October; we will update it once Octopus publishes Flux's October rates. In our calculator's reference case its net unit cost is about £56 a year on Octopus Flux (London rates), against £70.97 on a single-rate tariff at the July–September cap of 26.11p with 12p exports (needs Octopus as your electricity supplier), and £173.87 if it keeps its supplier and exports at 6p. Flux comes out ahead by about £15 a year over the 12p option, and that estimate doesn't sell stored energy at the 4pm peak. Our Octopus Flux guide shows the full working.

Heat pumps and Agile

Cosy Octopus suits a battery well, because its afternoon cheap period (13:00 to 16:00) comes just before the 16:00 to 19:00 peak. A battery that fills at 16.56p and covers the peak saves 29.04p per kWh charged (table above). Our calculator doesn't model Cosy yet, so we give no annual figure. Octopus's own estimate, about £82 a year, is for a typical heat pump home using 5,877 kWh a year on fixed Cosy rather than Octopus's standard fixed tariff; it doesn't include a battery or solar.

Agile Octopus follows wholesale prices every half hour. In London over the 30 days to 23 September 2026, prices averaged 24.73p without VAT, 15.62p between 10am and 4pm and 40.94p between 4pm and 7pm. They went below zero in 126 half-hours on 9 days, when Octopus pays you to use electricity, and peaked at 82.60p. These are simple averages, not a household's bill. Agile suits a battery with automation that charges in the cheapest slots and avoids the peak. A month of late-summer prices tells you little about winter, and Octopus warns that Agile prices can spike up to the cap at any time.

How to compare tariffs for your own home

1. Check the condition first. An electric car tariff is no use without a car, and Flux needs a battery.
2. Compare net bills, not headline savings. A saving "with this tariff" is measured against the same tariff without solar. Work out what you would pay in a year on each tariff, after export income, and include the standing charge.
3. Use your region's rates. Flux's peak export ranged from 27.17p to 30.68p across regions on 24 September 2026, and Intelligent Octopus Go's day rate from 34.55p to 38.42p.
4. Check the export pairing. Outgoing Octopus only works with certain Octopus import tariffs, and E.ON Next's 13p Export Exclusive excludes its time-of-use import tariffs. Our export tariff comparison lists the other suppliers' export rates.
5. Check your battery can follow the tariff. Standard Flux needs you to set a daily schedule; intelligent tariffs and add-ons such as Octopus's Charge Pack only work with supported brands.

Our calculator lets you choose a single-rate, cheap-overnight or import-and-export tariff and edit the rates for your region. It gives an estimate, not a quote.

This page covers Octopus's time-of-use tariffs, the ones our calculator uses as examples. Other suppliers sell time-of-use tariffs too; we didn't check their rates for this page. These tariffs apply in Great Britain: Octopus's price list has no Northern Ireland region, and the Smart Export Guarantee doesn't apply there.

Frequently asked questions

What is the best tariff for solar panels and a battery?

Of the Octopus tariffs we checked on 24 September 2026, the right one depends on your home. For a home with an electric car and a battery, Intelligent Octopus Go 12M Fixed with Outgoing Octopus's 12p export (needs a compatible car or charger and Octopus supply) beat a single-rate tariff by about £173 a year in our example. Without a car, Octopus Flux came out about £15 a year ahead of a single-rate tariff with 12p export (needs Octopus as your electricity supplier) at September prices. With a heat pump, Cosy Octopus is the one to check.

Can I charge my battery on cheap overnight electricity without an electric car?

Yes, on some tariffs. Octopus Flux charged 14.56p from 02:00 to 05:00 in London on 24 September 2026, Cosy Octopus has three cheap periods if you have a heat pump or electric heating, and Agile Octopus is often cheaper overnight. Intelligent Octopus Go and Octopus Go need an electric car.

Does Intelligent Octopus Go work with a home battery?

Yes, once you're on the tariff. Your whole home, including the battery, gets the 8p rate from 23:30 to 05:30. You need a compatible electric car or charger to join; a battery alone doesn't qualify.

Is Intelligent Octopus Flux available?

Not to most new customers. On 24 September 2026 it was open only to customers who bought solar panels and a battery from Octopus. Standard Octopus Flux was open.