Octopus Energy runs three tariffs that interact directly with home solar and battery systems: Flux, Go, and Cosy. Choosing right can mean £200–£400/year difference on a 13 kWh battery system.
Octopus Go (4 hours overnight cheap)
The original cheap-overnight tariff. 7p/kWh from 00:30 to 05:30, peak rate the rest of the time.
Best for: EV owners who can charge between 00:30 and 05:30, or homes that can run heat pumps/dishwashers/washing machines on overnight scheduling.
Solar interaction: minimal. Standard SEG export rate (15p/kWh).
Octopus Flux (best for batteries)
Three time bands: - 02:00–05:00: 17p import, 18p export (cheap charging window) - 05:00–16:00: 30p import, 30p export (mid) - 16:00–19:00: 36p import, 24p export (peak)
Best for: homes with a battery that can shift load. Charge at 17p overnight, discharge at peak, get 24p back per kWh exported during peak hours.
Solar interaction: massive. A 13 kWh battery on Flux makes £600–£900/year more than on Go.
Octopus Cosy (heat pump optimised)
Three time bands too: - 04:00–07:00 and 13:00–16:00: cheap (~10p) - 07:00–10:00 and 16:00–19:00: peak (~36p) - All other hours: standard (~28p)
Best for: heat pump owners. The cheap windows align with when heat pumps are most effective (cold pre-dawn, mild afternoon).
Solar interaction: moderate. Standard SEG.
The 2026 numbers, applied
For a 4 kW solar + 13.5 kWh battery system in Greater Manchester, on Flux:
- Annual generation: 3,400 kWh
- Self-consumed (with battery): 2,800 kWh saved at avg 30p = £840
- Exported during peak windows: 600 kWh at 24p = £144
- Bonus from cheap-rate battery cycling: ~£200/year (charge cheap, discharge peak when not solar generating)
Total: ~£1,184/year off the bill, vs ~£780/year on Go with the same hardware.
Switching costs
All three tariffs are no-fixed-term in 2026, so you can switch freely. Octopus offers in-app switching that takes effect within 14 days. Re-register your SEG payments with the new tariff in the same app.