Why Heat Pump Tariffs

Why Heat Pump Tariffs Beats Generic Comparison Sites

Ashley ·

Generic energy comparison sites are built for average households on flat-rate tariffs — not heat pump owners running time-of-use tariffs with usage that shifts by season and time of day. Heat Pump Tariffs uses your actual half-hourly smart meter data instead of national averages, so the comparison reflects how your heat pump really runs. Here's why that distinction matters, and what it actually changes about the numbers you see.

Why Heat Pump Tariffs Beats Generic Comparison Sites

If you've ever run your details through a big-name comparison site and then looked at your actual bill, you've probably noticed the numbers don't quite add up. That's not a bug — it's a structural limitation. Generic comparison sites were built for a different kind of household than yours.

The core problem: averages vs your actual usage

Most comparison sites estimate your consumption using one of two methods:

  • National average bands (e.g. "low/medium/high" usage profiles based on Ofgem's typical domestic consumption values)
  • A flat annual kWh figure you type in manually, spread evenly across the year

Neither of these reflects how a heat pump actually behaves. Heat pump load is heavily skewed by:

  • Season — a heat pump might use 10x more electricity in January than in July
  • Time of day — if you're on a time-of-use (TOU) tariff like Cosy Octopus or EDF FreePhase, your costs depend on when the heat pump and cylinder run, not just how much they use overall
  • Weather sensitivity — heating demand tracks outdoor temperature far more tightly than general household electricity use does

A flat-rate estimate averages all of this away. On a TOU tariff, that's not a small rounding error — it can be the difference between a tariff that looks cheap on paper and one that's actually cheaper for your home.

What we do differently

Heat Pump Tariffs is built around one core idea: compare tariffs using your real consumption pattern, not a generic stand-in for it.

Half-hourly smart meter data. Once you connect via the Bright app or upload a CSV export, every comparison runs against your actual half-hourly usage — the same granularity your TOU tariff bills you on. If your usage is genuinely highest at 4am because that's when your cylinder heats, the comparison reflects that, not a smoothed-out daily average.

Region-aware TOU rates. Many heat pump tariffs price differently by DNO region — Cosy Octopus variable rates, British Gas Heat Power, and ScottishPower Heat Pump Saver all vary regionally. A site working from a national average can't surface that difference. We match your tariff comparison to your actual DNO region.

Built for time-of-use structure, not just unit rate. Generic sites are typically optimised to compare a single unit rate and standing charge. Heat pump tariffs often have two, three, or four rate bands across the day. Comparing them properly means modelling your usage against those bands — not just multiplying total kWh by an average rate.

No guessing on your behalf. We don't ask you to estimate your annual usage from memory or a rough bill total. If you've already started load-shifting or shifting your hot water cylinder timing, that's reflected directly in your data — a generic estimate has no way to capture behaviour changes like that.

Why this matters for the result, not just the process

The point of better data isn't accuracy for its own sake — it's that it changes which tariff actually comes out on top. A household that's shifted most of its heat pump and cylinder running into off-peak hours might do significantly better on a steep TOU tariff than a flat-average estimate would ever suggest. Conversely, a household whose usage is still spread evenly across the day might find that a TOU tariff a generic site recommended doesn't suit their pattern at all.

This is also why we built the comparison around your DNO region and real rate bands rather than a single "best buy" table. Two households on the same tariff in different parts of the country can have meaningfully different outcomes once regional pricing and standing charges are factored in — something a national best-buy list can't capture by design.

The trade-off, honestly

Using real data does mean a bit more setup than typing a postcode into a generic comparison box. You'll need to connect a smart meter via Bright or upload a CSV before you get a tailored result. We think that's a worthwhile trade for a comparison that's actually built around how your heat pump runs — but if you just want a fast, rough estimate, a generic comparison site will get you that faster. The difference is what you're trading speed for.

Getting started

If you want to see how this works for your own home, the fastest path is to set up your Bright account, then run your first comparison once your data is in. From there you can see exactly which tariff suits your real usage pattern — not a national average standing in for it.

Further reading

Ready to compare tariffs using your own data? Register free and connect your smart meter to get started.

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