Cosy Octopus 12M Fixed March 2026 v2 vs Heat Pump Saver Sep 2027 v1

Side-by-side comparison of Octopus Cosy Octopus 12M Fixed March 2026 v2 and ScottishPower Heat Pump Saver Sep 2027 v1 using real UK smart-meter data.

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The figures above use a modelled household. Your own saving depends on when you use electricity — run this comparison against your real half-hourly smart-meter readings to see numbers that match your usage.

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About these tariffs

Octopus
Octopus

Cosy Octopus 12M Fixed March 2026 v2

Time of Use Fixed
Full details & per-region rates
ScottishPower
ScottishPower

Heat Pump Saver Sep 2027 v1

Time of Use Fixed
Full details & per-region rates

Questions

We are still calculating the worked example for this comparison. The page refreshes nightly and will show a side-by-side cost once a full period of data has been modelled. The right tariff depends on usage pattern - shift workable load (EV charging, heat pump cycles, hot water) into the cheaper periods of each tariff to maximise the saving.

Cosy Octopus 12M Fixed March 2026 v2 is a time of use tariff from Octopus. Heat Pump Saver Sep 2027 v1 is a time of use tariff from ScottishPower. They differ in how the unit rate is structured across the day, which is what drives the cost difference for households with shiftable load.

We take a real UK home's half-hourly smart meter data over the previous 90 days and model the bill on each tariff using the supplier's current published rates and standing charges. Standing charges scale with the modelled period; unit rates apply per half-hour using each tariff's rate structure (standard, Economy 7, time-of-use bands, or wholesale-tracking). Full methodology and data sources are linked below.

Both Octopus and ScottishPower publish per-region rates across the 14 UK DNO areas. Click through to either tariff page below to see the rates and standing charge specific to your DNO. Some tariffs require a smart meter or have other eligibility criteria set by the supplier.

The cost calculation rebuilds every night using current rates. Page caching is one hour so repeat visits within the day are fast. If a tariff's rates change mid-day, you will see the new numbers on the next nightly refresh.

How this comparison is built. Every cost figure on this page comes from modelling real half-hourly UK smart-meter data against each supplier’s current published rates and standing charges. The calculation refreshes nightly. We earn a small commission when a switch completes via a referral link — it does not affect the price you pay.

Read the full methodology Where the data comes from