Best Electricity Tariffs for Heat Pumps — UK 2026

Your electricity tariff is the single biggest factor in heat pump running costs. The difference between the best and worst tariff is £637 per year for the same home. Here's every option compared.

Tariff Comparison — Same Home, Different Costs

Based on a typical 3-bed UK home needing 12,000 kWh of heat per year, with a heat pump running at COP 3.2 (3,750 kWh electricity consumed):

Octopus Cosy — The Best Tariff for Heat Pumps

Octopus Cosy is specifically designed for heat pump homes. It offers two daily off-peak windows with electricity at 7.5p/kWh:

• Overnight window: approximately midnight to 7am — ideal for heating your hot water cylinder
• Afternoon window: approximately 1pm to 4pm — keeps your home warm through the evening
• Peak rate: higher than the standard variable rate, so you need a hot water cylinder and heating schedule aligned to the off-peak windows

Who qualifies for Octopus Cosy?

• You must have an installed heat pump (MCS certificate required)
• SMETS2 smart meter installed
• Hot water cylinder (200L+ recommended)
• Available from Octopus Energy — you may need to switch supplier

Economy 7 — The Established Off-Peak Option

Economy 7 has been available for decades and offers cheap overnight electricity at around 10p/kWh for 7 hours (typically midnight to 7am). The daytime rate is higher than standard, so you need to shift most of your heating to overnight.

For heat pump owners, Economy 7 works well if you:

• Have a hot water cylinder (250L+ ideal) to store overnight heat
• Can programme your heat pump to run primarily during the off-peak window
• Have good insulation to retain heat through the day

Octopus Agile — Smart Pricing for Tech-Savvy Homes

Octopus Agile charges a different price every 30 minutes, based on wholesale electricity markets. The average is around 18p/kWh, but rates regularly drop below 10p during low-demand periods — and occasionally go negative (you get paid to use electricity).

Agile works best with a smart controller (like a Mixergy or myenergi Eddi) that automatically shifts your heat pump to the cheapest half-hour slots. Without one, you need to manually schedule heating around the cheapest windows — which changes daily.

How to Switch to a Heat Pump Tariff

1. Check your smart meter: You need a SMETS2 smart meter. If you have an old-style meter or SMETS1, contact your supplier to arrange an upgrade (free of charge).
2. Gather your MCS certificate: This proves your heat pump installation meets quality standards. Your installer provides it after the job.
3. Compare available tariffs: Use your annual kWh figure (from your heat pump monitoring or estimate above) to compare real costs, not just the p/kWh rate.
4. Switch supplier if needed: Switching takes 5 working days. There are no exit fees on most variable tariffs. Octopus Cosy requires you to be an Octopus customer.
5. Set your heating schedule: Programme your heat pump to run during off-peak windows. Most modern heat pumps have built-in timers or app controls.

Heat Pump Tariff vs Solar Panels

If you have solar panels, the tariff calculation changes. Solar generates free daytime electricity, which can power your heat pump directly. In this case:

• Spring/summer: Solar covers most or all of your heat pump electricity, making the tariff rate less important
• Winter: Solar output drops, so your tariff rate matters more for the remaining grid-drawn electricity
• Best combo: Solar + Octopus Agile or Cosy. Use free solar during the day, cheap grid electricity overnight

See our heat pump with solar panels guide for the full calculation.

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