Which tariffs are actually built for battery charging
A home battery is not really a solar accessory. It is a device for buying electricity when it is cheap and using it when it is expensive, and the tariff you pair it with decides how much that is worth.
Updated 25 September 2026 · written by the Clearline guidance team · 8 min read
The mechanism, in one paragraph
Off peak tariffs give you a window of a few hours where electricity costs a fraction of the standard rate. A battery lets you fill up during that window and then run the house from stored electricity through the expensive hours. Nothing about that requires sunshine, which is why a battery earns its keep in December as well as June.
The spread is the product
At the Ofgem average capped rate of 26.32p per kWh for October to December 2026, filling a battery at 6.99p and using it later saves 19.33p on every unit. Across 1,000 kWh cycled through the battery that is £193.30 you did not spend, before a single panel is involved.
The windows on offer
Off peak windows come from three different corners of the market: EV tariffs, heat pump tariffs and solar and battery tariffs. The battery does not care which one it is, as long as the cheap rate applies to the whole home rather than just the car.
| Tariff | Cheap rate | Window | Applies to |
|---|---|---|---|
EDF GoElectric Overnight | 6.99p | 11pm to 6am, seven hours | Whole home. EDF electricity account and a fully connected smart meter, £75 exit fee |
E.ON Next Drive Smart | 8.5p, fixed 12 months | 12am to 6am | Whole home. Smart meter with half-hourly consent, eligible EV and charger |
E.ON Next Drive | 9p | 12am to 6am | Whole home. Any EV, any charger, one-year fixed |
British Gas Electric Driver | 9p | 12am to 5am | Whole home. British Gas electricity customer. Peak reported at around 31p |
Octopus Intelligent Octopus Go | From 8p | 23:30 to 05:30, plus smart-scheduled charging up to six hours a day | Whole home during the window. Needs a compatible EV or charger controlled through the app |
British Gas Heat Power | Half price | 1pm to 4pm and 12am to 7am, 70 hours a week, paid as a weekly credit | Requires a heat pump or electric heating system, British Gas supply and a working smart meter |
Octopus Cosy Octopus | 51% below the regional day rate | 04:00 to 07:00, 13:00 to 16:00, 22:00 to 00:00 | Requires a heat pump, electric boiler or electric radiators. Peak 16:00 to 19:00 sits 50% above the day rate |
Checked 3 August 2026. Most of these tariffs require a qualifying appliance, so a battery alone will not get you onto them.
That last point is the practical constraint. There is no mainstream tariff that hands you a 7p overnight rate purely because you own a battery. The cheap windows are attached to an EV or to electric heating. If you have neither, your realistic options are the solar and battery structures below, or a standard tariff with an economy night rate.
The battery tariffs built for this
Octopus Flux is the product designed around exactly this behaviour. It runs a three-rate structure across the day, with a cheap window in the small hours, a middle day rate, and a peak from 4pm to 7pm. The intended pattern is to charge from the grid overnight, run on solar during the day, then discharge to the grid into the peak window when export is worth most.
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Octopus confirms the structure and the windows on its own page and publishes the export rates for each region. On 28 October 2026 they ran from 28.90p to 31.75p from 4pm to 7pm, 10.60p to 11.64p through the day and 4.50p to 4.94p between 2am and 5am. All three of those are export rates, so the spread is what you gain by holding a unit back for the peak window rather than exporting it overnight: about 24.40p to 26.81p per kWh, depending on region. The matching import rates are shown against a postcode on Octopus's page, so we do not quote one, and the charge-cheap-then-export version of the strategy cannot be priced here. Treat the three ranges as indicative, not as your quote.
Prime Outgoing Octopus is the simpler cousin: 16p for exports between 4pm and 7pm and 9p the rest of the day, on a 12-month fixed term, with no special import structure. Intelligent Octopus Flux, the automated version of Flux, is closed to new customers: Octopus lists it as temporarily unavailable and currently exclusive to customers who bought solar panels and a battery from Octopus.
Flux asks you to drive it
Flux expects manual battery scheduling. The automated variant that did the thinking for you is no longer open to new customers, so the value depends on you or your installation team setting the charge and discharge windows correctly and revisiting them when the tariff or your habits change.
What the arithmetic really looks like
Two separate gains are in play, and they are often confused with each other.
| Strategy | What you earn per kWh | Where it comes from |
|---|---|---|
Charge cheap, use it yourself | Up to 19.33p | 6.99p import against the 26.32p capped average you would otherwise pay |
Hold a unit for the peak instead of exporting it overnight | Around 24.40p to 26.81p, indicative | 4.50p to 4.94p overnight export against 28.90p to 31.75p peak export on Octopus Flux |
Store solar, use it yourself | 26.32p | A unit you generated and would otherwise have exported at 12p or less |
Store solar, export at peak | Around 16.90p to 19.75p more than a flat 12p rate | 28.90p to 31.75p peak export instead of 12p flat |
Import comparison uses the Ofgem average capped rate of 26.32p per kWh for 1 October to 31 December 2026. The Flux figures are all export rates, Octopus's regional rates as at 28 October 2026 rather than a quote. Round-trip losses are not deducted.
Round-trip efficiency is the honest asterisk on all of it. No battery returns every unit it takes in, so the real spread is a little narrower than the table shows. The same sum with the losses deducted, and the annual pounds it produces for each battery size, is in how much a battery saves on cheap night rates. It is still a wide margin at these prices, and it is the reason we treat the tariff as part of the battery decision rather than something to sort out afterwards.
Sizing the battery to the window, not to the roof
If off peak charging is a big part of your case, the battery needs to be big enough to carry the house from the end of the cheap window to the start of the next one. That is a different sizing question from covering an evening's solar shortfall, and it usually points to more usable capacity.
Measure the gap you are covering
From the end of the cheap window to the start of the next one is 17 hours on a 7am to 12am gap. Work out what your home draws across that stretch.
Check the window is long enough to fill it
Seven hours at a domestic charge rate puts a real ceiling on how much you can take in overnight. A very large battery cannot be filled inside a five-hour window.
Decide whether you are exporting at peak
If a Flux-style peak export window is part of the plan, the battery needs headroom to hold charge for it rather than spending everything on the house.
Pick the tariff and the battery together
The right answer changes depending on which window you can qualify for, which is why the two decisions belong in the same conversation.
Our sizing guide works through the capacity side, and every county page in our coverage area carries a calculator that compares filling the battery from solar against filling it from an off peak rate, then reports whichever wins for that configuration.
Bring your usage pattern to a free design call and we will model the off peak case against the solar case for your home.
Get my free quote →Where this stops working
- No qualifying appliance. Most cheap windows require an EV or electric heating. A battery on its own rarely unlocks one.
- A punishing peak rate. These tariffs fund the cheap window with an expensive one. British Gas Electric Driver's peak is reported at around 31p, and Cosy Octopus sets its 16:00 to 19:00 peak 50 per cent above the day rate. If the battery is empty at 5pm you are paying that rate.
- Meter problems. Half-hourly settlement depends on a smart meter that is actually communicating. A dropped connection quietly costs you the tariff.
- Export tariff clashes. E.ON Next excludes time-of-use import tariffs from its Export Exclusive v3 export rate, so pairing a cheap import window with a good export rate is not always possible within one supplier.
- Fixed terms end. Almost all of these are 12-month products. Model the value over the life of the battery, not the life of the tariff.
The full import and export picture is set out in the export rates comparison and the EV tariffs comparison, and the tariffs overview ties them together.
All tariff structures verified against supplier pages on 3 August 2026, except the Octopus Flux regional export rates, read from Octopus's published data on 28 October 2026.
Off peak charging questions, answered
Can I get a cheap overnight rate just for a battery?
Rarely. The mainstream off peak windows are attached to an EV tariff or an electric heating tariff, so they need a qualifying car, charger or heat pump. Solar and battery specific structures such as Octopus Flux are the main exception, and they come with their own conditions.
How much does off peak battery charging actually save?
The gain is the spread between the cheap rate and what you would otherwise pay. At 6.99p against the 26.32p average capped rate, that is 19.33p per kWh, or £193.30 across 1,000 kWh cycled. Round-trip losses in the battery shave a little off that in practice.
Is it better to charge the battery from solar or from the grid?
In summer, solar usually wins because the electricity is free at the point of generation. In winter, an off peak rate often wins because there is not enough generation to fill the battery. A well-set-up system does both, choosing whichever is cheaper on the day.
Does charging from the grid stop me claiming export payments?
No, but it changes what you are exporting. Suppliers price battery exports differently, which is why OVO pays up to 20p with a battery and 15p without one on its install-exclusive rate. Where a battery is fitted, expect the supplier to ask for schematics as part of the application.
What is Octopus Flux and who is it for?
It is a three-rate tariff for homes with both solar and a battery, importing and exporting with Octopus. The pattern is cheap overnight import, solar through the day, then export into the 4pm to 7pm peak window. It requires manual battery scheduling, because the automated version is closed to new customers.
Will a bigger battery always earn more on an off peak tariff?
Only up to the point where you can fill it inside the cheap window and empty it before the next one. Beyond that you are paying for capacity that never cycles. Match usable capacity to the consumption you need to carry between windows, not to the largest unit on the price list.
See the numbers next: Duracell Dura16, installed, or export rates compared.
Figures and specifications in this guide are sourced below and were checked on the date shown. Rates and product specifications change; we confirm the current picture on your free design call.
Sources
- Octopus Energy, Flux three-rate structure and export window, accessed 3 August 2026 octopus.energy
- Octopus Energy, Prime Outgoing Octopus rates and term, accessed 3 August 2026 octopus.energy
- Octopus Energy, Cosy Octopus windows and rate structure, accessed 3 August 2026 octopus.energy
- EDF, GoElectric Overnight rate, window and exit fee, accessed 3 August 2026 edfenergy.com
- E.ON Next, Next Drive and Next Drive Smart rates and windows, Next Drive Smart re-checked at 8.5p on 25 September 2026 eonnext.com
- British Gas, Heat Power half-price windows and weekly credit mechanism, accessed 3 August 2026 britishgas.co.uk
- Ofgem, average capped electricity unit rate for 1 October to 31 December 2026, accessed 25 September 2026 ofgem.gov.uk
- Octopus Energy, Flux regional export rates (public API) and Intelligent Octopus Flux availability, accessed 28 October 2026 octopus.energy
- Bestchargers, reported British Gas Electric Driver peak rate (secondary source) bestchargers.co.uk
Read next
Choosing a tariff when you have solar, a battery and an EV
Solar, battery and EV want different tariffs. How to work out which one to protect.
Read the guide →Why the best export rates always carry conditions
The top export rates are acquisition offers. Here is how to price the condition.
Read the guide →How much a battery saves by charging on cheap night rates
What charging at 8.5p and using at 26.32p is actually worth over a year.
Read the guide →