Octopus Agile import · Outgoing fixed 12p export
The tariff
The tariff matters as much as the hardware, because it decides what every stored kWh is worth. Ours changed while we were waiting for install day. If you're planning a battery system around any time-of-use tariff, this story is worth two minutes.
The Flux plot twist
The original business case was built on Octopus Flux, the classic battery tariff with a cheap overnight window and a 30p evening export peak. The plan was simple: charge cheap overnight, force-export the battery into the 4pm to 7pm peak, profit. Then in March 2026 Flux (and Intelligent Octopus Flux) closed to new customers, months before our panels went on the roof. So much for the plan.
Lesson one: never build a multi-year payback case on a single tariff surviving. Tariffs are products, and products get withdrawn. Model your second-best option too. We hadn't, and re-planning under time pressure wasn't fun.
What we run now
| Side | Tariff | Shape |
|---|---|---|
| Import | Octopus Agile | Half-hourly dynamic pricing, published around 4pm for the next day, capped at £1/kWh. Cheap slots in the low teens; evening import peaks range from the mid-20s in summer to the high 30s in winter. |
| Export | Outgoing Octopus (fixed) | Flat 12p/kWh at all times. There are no export peaks on this tariff. Boring on purpose: it's a guaranteed floor. |
Export isn't switched on yet. We can't be paid for export until the final installation certification goes in, which can take a month or two from install day. Until then the export tariff is signed up but dormant, and the stats honestly report £0 export revenue. The battery soaks up most of the surplus anyway, which softens the blow.
Surprisingly, losing Flux's 30p export peak only cost us around 10% of the projected year one return. The reason is that under Agile the battery's job flips from exporting at a peak rate to not importing at a peak rate. Dodging expensive evening import is worth about as much as the old peak export was, and Predbat reorganised the whole strategy by itself the day we changed the rate sensors. The only real loss is on true surplus (battery full, house satisfied), which now earns 12p instead of 30p.
A possible upgrade later: Agile Outgoing offers half-hourly export pricing, uncapped, with no exit fees. For battery owners who can export selectively into evening spikes it can beat a flat 12p, and winter wholesale prices occasionally clear 50p or more. We'll switch if the data shows our would-be Agile export revenue reliably beating 12p. That comparison is exactly the kind of question this site's dataset exists to answer.
Why Octopus at all?
Higher flat export rates do exist elsewhere (E.ON around 16.5p, British Gas around 15p), but they all require importing with the same supplier on a flat or simple time-of-use tariff. For a Predbat home, the cheap-import arbitrage on Agile is the bigger prize. Octopus also has the best API in the business, which the whole automation stack hangs off.
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