How Octopus Flux works
Octopus Flux is a symmetric tariff built around three price periods that repeat every day. From midnight to 6am, import is cheap at approximately 8-10p/kWh. From midday to 4pm, a premium export rate of approximately 15-20p/kWh rewards solar generation. The rest of the day runs at a standard flat rate of approximately 24-26p/kWh.
The design logic is straightforward: charge your home battery during the cheap overnight window, discharge it or export your solar during the midday peak export window, and avoid grid draw during the standard rate periods. For households with both solar and battery storage, Flux creates a clear daily rhythm: cheap in overnight, expensive out at midday. The tariff is predictable. You always know exactly what you will be charged and credited.
Flux requires a smart meter and an export meter (G100 or similar). You need to be with Octopus Energy. A home battery is not strictly required, but the tariff is designed to be most rewarding when you have one. A battery lets you buy cheap overnight electricity and export it (or discharge it for self-consumption) during the midday window, capturing the full spread between 8-10p import and 15-20p export or self-consumption value.
How Agile works for solar homes
Agile is a fully dynamic tariff. Prices change every 30 minutes based on the wholesale electricity market. Overnight prices typically run 2-8p/kWh with frequent dips to below 5p and occasional plunge pricing events going negative. Daytime prices vary widely: 8-20p/kWh on normal days, spiking to 35-50p/kWh during winter demand peaks.
For solar owners, Agile's dynamic nature works in both directions. On sunny days when your solar is generating and you are not buying grid electricity, daytime price volatility is irrelevant. You are self-consuming for free. The Agile price only matters when solar is not covering your consumption, typically in the evenings and overnight. At those times, Agile's cheapest periods deliver import costs well below any fixed-rate tariff including Flux.
Export on Agile is handled separately via the Smart Export Guarantee. You contract with Octopus Outgoing or another SEG provider for your export rate, which runs at approximately 15-20p/kWh in 2026. This export rate is fixed or semi-fixed, separate from the dynamic import rate. The practical result: you get the benefit of dynamic cheap import via Agile and a competitive fixed export rate via SEG.
The export comparison: Flux midday rate vs SEG
On Flux, your solar exports during the midday window earn 15-20p/kWh. On Agile, your solar exports earn the SEG rate via Octopus Outgoing, which is also approximately 15-20p/kWh. The export rates are broadly comparable across both tariffs.
The main distinction is timing flexibility. Flux's export premium applies specifically to the midday-to-4pm window. Solar generation during this period aligns well with the UK solar peak, so most of your surplus is captured at the premium rate. Generation outside this window, particularly in the late morning or late afternoon, earns the standard flat rate rather than the export premium.
On Agile via SEG, your export is credited at the same rate regardless of when you export. If your solar generation peaks at 11am or at 3pm, you earn the same SEG rate. There is no time-window premium to hit, but there is also no bonus for perfect midday generation.
Overall, households with strong 11am-3pm solar generation find Flux's midday export rate marginally better aligned. Households with generation that spreads outside this window, or who self-consume most of their solar and export little, find the SEG rate on Agile equally competitive.
The import comparison: Flux cheap window vs Agile overnight
This is where the two tariffs diverge most clearly, and where Agile tends to win for most UK households.
Flux's overnight cheap window runs midnight to 6am at a fixed 8-10p/kWh. The rate is guaranteed and predictable. Over 2,000 kWh of overnight import per year, you pay £160-200.
Agile's overnight rate in the same midnight-to-6am window typically averages 3-6p/kWh. Some nights are cheaper, some are slightly more expensive. Plunge pricing events go negative, earning you money to import. Over the same 2,000 kWh annually at an average Agile overnight rate of 4p/kWh, you pay £80. Compared to Flux, that is a saving of £80-120 per year on overnight imports alone.
The trade-off is predictability. Agile prices vary nightly. You cannot guarantee exactly what tomorrow's overnight rate will be. Some nights Agile overnight prices might run 7-8p, reducing or eliminating the advantage over Flux. But across a full year, Agile's overnight average consistently beats Flux's fixed rate by 2-5p/kWh in most UK regions. Check tonight's Agile prices to see the current overnight window in your region.
Battery strategy under each tariff
Batteries interact differently with Agile and Flux, and the strategy shifts accordingly.
Under Flux, the optimal battery strategy is to charge in the midnight-to-6am window at 8-10p and discharge during the midday-to-4pm window, either through self-consumption at home or by exporting at 15-20p. The arbitrage spread is 5-12p/kWh. A 10kWh battery cycling once daily on this spread captures £0.50-1.20 per cycle, approximately £180-440 per year.
Under Agile, the optimal strategy is to charge during the cheapest overnight Agile slot (often 1am-5am at 2-5p/kWh) and discharge during the early evening peak (4pm-9pm at 20-45p/kWh). The arbitrage spread is typically 20-40p/kWh. A 10kWh battery cycling on this spread captures £2-4 per cycle, approximately £700-1,460 per year.
Agile's battery arbitrage spread is substantially larger than Flux's because Agile's overnight prices are lower and its peak prices are higher. The downside is variability: some nights the overnight Agile rate is higher than usual, narrowing the spread. Over a full year, Agile battery arbitrage typically outperforms Flux battery arbitrage by £300-600 annually on a 10kWh system.
Head-to-head comparison
| Feature | Octopus Agile | Octopus Flux |
|---|---|---|
| Overnight import rate | 2-6p/kWh average | 8-10p/kWh fixed |
| Daytime import rate | 8-45p/kWh (variable) | 24-26p/kWh flat |
| Export mechanism | SEG via Octopus Outgoing ~15-20p | Midday export rate ~15-20p |
| Battery arbitrage spread | 20-40p/kWh typical | 5-12p/kWh typical |
| Best for | Battery owners, overnight importers | High solar exporters, simple setup |
The household profiles: which tariff suits you
The comparison is not one-size-fits-all. Different household profiles point toward different tariffs.
High exporter with large solar (5kWp or above): If you reliably export 3,000+ kWh per year into the midday window, Flux's predictable midday export rate and simpler structure may suit you. Your export income is clear and guaranteed. Flux removes the complexity of Agile price monitoring.
Average household with 3-4kWp solar, mostly self-consuming: Agile wins on overnight import cost. You export relatively little, so Flux's midday export premium adds limited value. Cheaper overnight Agile rates reduce your annual grid bill by £80-140 compared to Flux.
Battery owner prioritising arbitrage: Agile wins clearly. The overnight-to-peak arbitrage spread on Agile is 3-5 times wider than on Flux. If maximising battery arbitrage return is your priority, Agile is the tariff.
No battery, solar only: Agile provides better overnight import rates. Flux's structure offers no meaningful advantage without a battery to capitalise on the midday export window. Agile is the stronger choice.
Can you switch between them?
Yes. Both Agile and Flux are Octopus tariffs with no exit fees or long-term commitment. You can switch between them at any time through your Octopus account with typically one billing period's notice. The practical approach for uncertain households: try Agile for two months, then Flux for two months, compare your actual bills, and stay on whichever produced the lower cost for your specific consumption pattern.