Where Our Tariff Data Comes From
Supplier sources, refresh cadence, and our independence policy.
The short version
Every electricity tariff we compare is sourced directly from the supplier - either through their public API or from a publicly published rate sheet. Rates are refreshed automatically every day.
We do not pay suppliers to be included, and suppliers do not pay us to influence rankings. Every tariff is modelled identically against your real smart meter data, regardless of whether the supplier has a referral agreement with us or not.
Coverage spans every major UK supplier with a heat-pump-relevant tariff, across all 14 UK DNO regions.
Suppliers and sources
We track tariffs from the following UK electricity suppliers. The list is updated as new heat-pump-relevant tariffs become available.
| Supplier | Tariff types covered | Source | Refresh |
|---|---|---|---|
| Octopus Energy | Standard, Economy 7, Time of Use, dynamic | Octopus / Kraken public API | Daily |
| EDF | Standard, Time of Use, dynamic | EDF Kraken API + published rate sheets | Daily |
| E.ON Next | Standard, Time of Use | Kraken API (user-side fetch) | Daily |
| ScottishPower | Standard, heat-pump-specific | Published rate sheets | Daily |
| British Gas | Standard, heat-pump-specific | Published rate sheets | Daily |
| Good Energy | Standard, heat-pump-specific | Published rate sheets | Daily |
Live counts of suppliers and tariffs are shown on the homepage stats bar and update as our coverage grows.
Smart meter data (your usage)
When you connect a smart meter, your half-hourly consumption is pulled via the free Bright app from Hildebrand, running on the Glowmarkt platform. This is the industry-standard third-party route for accessing smart meter data on the UK DCC network.
- Works with all SMETS1 and SMETS2 smart meters in Great Britain.
- Access is read-only — we cannot send anything back to your meter.
- Data is pulled once daily once your account is linked.
- You can revoke access at any time from your account settings or directly within the Bright app.
If you prefer not to link Bright, you can also upload a half-hourly CSV exported from your supplier's app or website. Both routes feed into the same comparison engine.
DNO regions
Electricity rates in the UK vary by Distribution Network Operator (DNO) region — there are 14 of them. We track all 14 and apply the rates that actually apply where you live. Standing charges in particular vary by region, often by more than 10p per day between the cheapest and most expensive area.
See the UK electricity tariffs by region hub for a per-region breakdown.
Independence and conflicts of interest
What we do:
- Apply every tariff to your usage data using the same engine and the same logic.
- Rank tariffs purely by the cost they would have produced against your real consumption pattern.
- Disclose any affiliate / referral relationship next to the switch link on the relevant tariff page.
What we do not do:
- Accept payment from suppliers in exchange for inclusion, ranking, or favourable placement.
- Hide or suppress a supplier's tariff because they do not offer a referral.
- Sell, share, or monetise your smart meter data.
Technical detail (refresh schedule, snapshot pattern, failure handling)
Refresh schedule
A scheduled job runs daily during the early UK morning to refresh:
- Supplier rate fetches — Octopus / Kraken endpoints are polled and any new rate version is written to the database. Existing versions are closed at the new version's start date, preserving the full history.
- Region snapshots (around 04:10 UTC) — one JSON file per DNO region, listing the live tariffs available in that region with their current rates.
- Tariff snapshots (around 04:15 UTC) — one JSON file per tariff group, with its current rates and rate history.
Pages serve from these JSON snapshots, not from live database queries — this is why region and tariff pages load fast and reliably even during peak traffic.
Rate history
Every rate version is preserved with the date it took effect and the date it was superseded. The per-tariff history chart on each tariff page is drawn directly from these versioned records, so you can see how a tariff has changed over time.
What happens if a supplier API is unavailable
If a daily fetch fails or returns malformed data, the existing rate is left in place rather than being overwritten with bad data. The fetcher logs the error and retries on the next scheduled run. Defensive guards compare incoming rates against the most recent version before allowing a close-and-insert cycle, preventing accidental loss of rate history.
Data validation
- Rate comparisons use a small epsilon to avoid floating-point false-positives.
- Time-of-use band times are stored in UK local time; half-hourly meter readings are stored in UTC. Conversion is applied per slot in the comparison engine, with explicit handling for BST / GMT transitions.
- DST spring-forward days have 46 slots rather than 48 — this is recognised by the comparison engine and is not treated as a partial day.
What is not included
- Exit fees and other contractual charges associated with leaving your current tariff.
- Future rate changes announced but not yet in effect (we apply each tariff at its rates for the period being compared).
- Non-standard meter setups (e.g. dual-rate meters with unusual band schedules) outside the published tariff structure.