How we calculate
Every figure on your results page comes from one calculation, applied identically to every plan. Nothing is reordered for commission, and no plan is hidden.
Your usage
Your file contains a reading for every half hour. We classify each half hour into the plan's price bands (day, night, peak, EV window…), sum the energy in each band, and scale to 365 days. If your file covers less than about ten months we say so — a full year captures winter/summer patterns best. Exported units (solar) are totted up the same way.
Each plan's cost
- Band energy × that band's unit rate (stored ex-VAT, from the supplier's own price sheet — every plan links its source).
- Plus the standing charge and the PSO levy (€17.52/yr ex-VAT, set by the CRU).
- VAT at 9% on all of the above.
- Minus export credit: your exported kWh × the plan's Clean Export Guarantee rate (not VATable).
- Year 1 subtracts sign-up discounts and welcome credits; year 2 is the same plan at full rates — both are shown, because "30% off" plans often flip order in year 2.
What we assume
- Urban standing charges; direct debit + e-billing rates (the ones suppliers advertise). Rural standing charges are higher.
- Plan requirements (direct debit, e-billing, contract length, exit fees) are listed per plan, not silently ignored.
- Some plans have quirks we flag but don't model — e.g. fair-use caps on EV bands. They're in the plan's notes.
- Rates change often. Every plan carries the date we last verified it (currently 2026-09-14) and we re-check when suppliers announce changes.
Accuracy check
Our engine is tested against the suppliers' own published "Estimated Annual Bill" figures: running the CRU's standard 4,200 kWh profile through our calculation reproduces each supplier's published EAB to within €5. That test runs automatically whenever we change anything.