Octopus Go vs Flux: Which Tariff is Best for Solar?

The two main options for solar households

If you've got solar installed (or you're planning to), the tariff you're on can make as big a difference to your bills as the panels themselves. For most of our customers, the decision comes down to two Octopus tariffs: Go or Flux. Here's how they compare.

Octopus Go: simple, predictable, battery-friendly

Octopus Go gives you a heavily discounted rate for a fixed 5-hour overnight window (typically 00:30 to 05:30), and a standard rate for the rest of the day.

How it works with solar + battery:

• Battery charges from the grid at the cheap overnight rate
• House runs off the battery and solar during the day
• Excess solar exports back to the grid for SEG income
• Battery tops back up overnight

Best for: Solar households with a battery who want a "set it and forget it" approach. Particularly good if you also have an EV — the cheap rate covers both car and battery charging.

Watch out for: The daytime rate on Go is slightly higher than a standard tariff. If your battery isn't sized properly or it runs out by 4pm, you could end up worse off than a flat-rate tariff.

Octopus Flux: dynamic pricing for solar + battery

Flux is designed specifically for households with solar and battery storage. Import and export rates change three times a day:

• Off-peak (02:00-05:00) — cheap import (charge battery)
• Peak (16:00-19:00) — expensive import, but also high export rate (sell from battery)
• Day rate (rest of the day) — standard import and export

How it works with solar + battery:

• Battery charges from grid overnight (cheap)
• Solar tops up battery during the day
• Battery exports back to grid during the peak teatime window at the high export rate
• Repeat

Best for: Households with larger battery capacity (10kWh+) and bigger solar arrays who want to maximise income from exports. Works particularly well with smart batteries like the Sigenergy SigenStor that can be programmed to discharge to grid on a schedule.

Watch out for: Flux requires active management or smart battery software to really pay off. If you're just running default settings, you may not see much benefit over Go.

So which one should you pick?

As a rough rule of thumb:

• Smaller system, simple needs, no EV — Go is usually fine
• Solar + battery + EV — Go (covers car charging too)
• Larger system, big battery, active user — Flux can pay better, but needs setting up properly
• No battery — Neither — stick with a standard tariff plus Outgoing Octopus for export

What about the export rate (SEG)?

SEG (Smart Export Guarantee) is what you get paid for excess solar sent back to the grid. Octopus's standard export rate on the Outgoing Octopus tariff is paid alongside whichever import tariff you're on.

If you've got a big system with significant excess generation in summer, the export rate matters a lot. If your battery soaks up most of your excess, less so.

How we set this up for our customers

When we install a Sigenergy SigenStor system, we configure the battery management software to match whichever tariff you're on. That means:

• Automatic overnight charging windows
• Solar self-consumption priority during the day
• For Flux customers — scheduled discharge to grid during peak hours
• Smart switching if the tariff structure changes

It's all done in the app — you don't have to think about it. But we'll always talk you through how it works, so you understand what's happening.

Want to talk it through?

If you're trying to work out which tariff makes sense for your setup, drop us a line. We're not financial advisors, but we've helped over 200 households figure this out and we'll give you straight advice based on what you're trying to achieve.