Great Britain Heat-Pump Electricity Tariffs: Compare Unit Rates and Standing Charges

A tariff with a lower electricity unit rate may still cost more overall if its daily standing charge is higher. The reverse can also happen for a home that uses a lot of electricity. A heat-pump owner should compare offers using expected post-installation use, the times the system runs, and charges the household would actually pay. There is no universally cheapest tariff without the home’s usage pattern and eligibility details.

Compare the same use across offers

For a single-rate tariff, a simple annual electricity-cost estimate is:

annual use in kWh × unit rate + standing charge per day × days charged

Then add or account for any applicable bill components, taxes, discounts, and payment terms according to the offer. Keep the household’s existing non-heating electricity use in the same comparison if the purpose is to choose a whole-account tariff. If you are isolating the heat-pump contribution, state that clearly and remember the standing charge may apply to the account whether or not the heat pump is installed.

Here is an invented example to show why both numbers matter. Offer A has a unit rate of 29p/kWh and a standing charge of 26p/day. Offer B has a unit rate of 31p/kWh and a standing charge of 18p/day. At 4,000 kWh in a year, A costs £1,160 for units plus £94.90 in standing charges, or £1,254.90. B costs £1,240 for units plus £65.70 in standing charges, or £1,305.70. At that usage, A is £50.80 lower before any other offer-specific charges or discounts. These values are hypothetical arithmetic, not current tariff quotes or a recommendation.

The break-even use for these invented offers is 1,460 kWh per year: the 8p/day standing-charge difference across 365 days is £29.20, offset by a 2p/kWh unit-rate difference at 1,460 kWh. Below that use, B’s lower daily charge can offset its higher unit rate; above it, A’s cheaper unit rate can outweigh its higher daily charge. A real comparison should use the supplier’s exact rates, contract period, and any conditions.

Match the tariff to the heat-pump load

Heat pumps do not use the same amount of electricity every hour of the year. Cold weather, hot-water recovery, defrost, backup resistance, room controls, and occupancy affect timing and quantity. If an offer has peak and off-peak rates, estimate the home’s use in each band rather than applying the cheapest rate to every kilowatt-hour. A smart meter or supplier data can help describe a current household profile, though a post-installation load may differ.

Compare the full bill boundary. The electricity standing charge is usually an account-level cost rather than a heat-pump-only charge, so count it as a change only if the tariff or account setup changes it. If gas remains for another appliance, its charge may also remain. If the heat pump replaces the only gas use and the account can close, confirm which gas costs actually end. Check whether the quote or model includes all electric heating and hot-water uses that will move onto the meter.

Treat Ofgem figures and pilot tariffs as dated context

Ofgem publishes regional price-cap unit rates and standing charges for default tariffs and defined periods. The table checked on 29 October 2026 covers 1 October–31 December 2026. The cap changes over time and differs by region, payment method, and meter arrangement. It is a reference ceiling for eligible default tariffs, not a household’s total bill or a description of every fixed deal. Northern Ireland has a separate regulatory context, and fixed tariffs are not the same as a price-cap variable tariff. Check the current period and region before using any benchmark.

Ofgem’s one-year lower-standing-charge pilot began in June 2026 for eligible customers of participating Great Britain suppliers. A lower daily charge may come with a higher unit rate, so an individual customer’s total could be higher or lower depending on consumption. Availability and terms are supplier-specific; the pilot is not a universal heat-pump tariff and does not prove a household will save.

A practical comparison checklist

Before switching, collect the current annual kWh use, a realistic post-heat-pump estimate, time-band profile if applicable, each offer’s unit rates and daily charges, meter requirements, payment terms, contract duration, exit fees, and eligibility conditions. Compare one full year and, when heating loads are seasonal, inspect the winter months separately. Run low, central, and high heat-pump-use cases. Include gas or other charges that remain and avoid assigning a whole-account fixed fee to the appliance unless the decision actually changes it.

Use supplier pages for current offers and confirm the final terms before signing. Tariff comparisons can inform an operating-cost estimate, but do not establish heat-pump performance, installation quality, or total project payback. For air-to-air systems, see the whole-system UK cost guide; for broader project assumptions, see the payback calculator guide.