Octopus Cosy Tariff for Heat Pump Owners: The Complete Guide

Nine hours of electricity at 10p per kWh instead of 24.5p. That is the core promise of Octopus Cosy, and for most heat pump owners, it translates to savings of £300-500 per year with nothing more than a tariff switch and some heating schedule adjustments.

This guide covers everything you need to know about Cosy Octopus: how the three daily off-peak windows work, current rates for 2026, eligibility requirements, and the scheduling strategies that squeeze the maximum savings from every cheap kilowatt-hour.

How Octopus Cosy Works

Unlike a standard electricity tariff where you pay the same rate all day, Cosy divides the day into three rate tiers designed specifically around how heat pump households use electricity.

The genius of Cosy is the three off-peak windows giving you nine hours of cheap electricity per day. The early morning window lets you pre-heat the house before waking. The afternoon window provides a mid-day boost. The late evening window is perfect for heating your hot water cylinder overnight.

Current Cosy Octopus Rates (Q1 2026)

Rates as of March 2026 (South England region — other regions vary slightly):

These rates are variable and Octopus can adjust them, typically in line with Ofgem price cap changes each quarter. The off-peak rate has remained consistently below 12p/kWh since the tariff launched, which is roughly 60% cheaper than the standard rate.

Who Is Eligible for Cosy Octopus?

You need to meet three requirements:

1. A heat pump: Air source, ground source, or hybrid heat pump. You will need to provide evidence of your installation — typically your MCS certificate or heat pump serial number
2. A smart meter: SMETS2 preferred, but upgraded SMETS1 meters work too. If you do not have one, Octopus will arrange a free installation
3. An Octopus Energy account: You need to be an Octopus electricity customer. If you are with another supplier, you will switch to Octopus first

The tariff covers your entire household electricity supply — not just the heat pump. This means all your appliances, lighting, and other electrical use are also billed at the Cosy rates.

How Much Can You Save on Cosy?

The 3-bedroom home saves £497 per year. The 4-bedroom detached saves £630 per year. These are realistic figures, not best-case scenarios. Homeowners with excellent insulation who aggressively schedule their heating report savings of £600-800 per year.

Over the typical 15-20 year lifespan of a heat pump, those savings contribute significantly to recovering the installation cost.

How to Maximise Savings on Cosy

Schedule Your Heat Pump Properly

The single most important thing you can do is align your heat pump schedule with the off-peak windows:

• Morning pre-heat (4am-7am off-peak): Set your heat pump to raise the house temperature to your preferred level by 7am. The house then coasts on stored heat through the morning
• Afternoon boost (1pm-4pm off-peak): Top up the temperature during the second cheap window, particularly valuable in winter
• Avoid the peak (4pm-7pm): Set your thermostat 1-2 degrees lower during peak to prevent the heat pump kicking in
• Hot water (10pm-midnight off-peak): Schedule your hot water cylinder reheat to 50-55 degrees during this window

Improve Your Insulation

The better your home holds heat, the less you need to run your heat pump during expensive periods. Even relatively cheap improvements like loft insulation top-up (£300-400) and draught-proofing (£100-200) make a noticeable difference to how long your home coasts between off-peak windows.

Use Solar to Cover Standard-Rate Hours

If you pair Cosy with solar panels, you generate free daytime electricity covering those standard-rate hours. Combined with cheap off-peak heat pump electricity, total annual heating costs can drop below £400.

Common Mistakes on Cosy Octopus

• Running on default settings: Weather compensation modes run whenever the house needs heat, regardless of tariff pricing. Schedule manually for best savings
• Ignoring non-heat-pump usage: Cosy applies to all electricity. Shift laundry and dishwasher cycles to off-peak using delay timers
• Setting flow temperatures too high: Running above 45 degrees reduces COP, consuming more kWh during each off-peak window
• Not monitoring usage: Review the Octopus app weekly to spot accidental peak-hour heat pump operation

Cosy Octopus and Solar Panels

If you have solar panels, Cosy becomes even more powerful. During spring and summer, your solar panels generate free electricity during the day, meaning you barely draw from the grid during standard-rate hours. Combined with cheap off-peak overnight electricity for your heat pump, your annual electricity cost drops dramatically.

Octopus also offers export tariffs for surplus solar generation, meaning excess solar energy earns you money whilst your heat pump runs on cheap off-peak electricity.

Switching to Cosy Octopus

1. Go to the Octopus Energy website and get a quote for your postcode
2. Sign up (or switch from your current supplier — Octopus handles the transfer)
3. Once your account is active, request the Cosy tariff through your Octopus account
4. Provide your heat pump details (MCS certificate, make and model, installation date)
5. Octopus verifies your heat pump and activates Cosy — usually within a few days
6. If you need a smart meter, Octopus arranges a free installation (may take 2-4 weeks)

There is no lock-in and no exit fees. If Cosy does not suit you, switch to another Octopus tariff or leave entirely at any time. For a broader comparison, see our best heat pump tariff guide.

Frequently Asked Questions

Can I use Cosy Octopus with a ground source heat pump?

Yes, Cosy is available for all heat pump types including air source, ground source, and hybrid systems. The scheduling principles are identical — align your heat pump's operation with the off-peak windows to maximise savings.

Do I need to be home during off-peak windows for Cosy to work?

No. Your heat pump operates automatically based on the schedule you set. The house heats up during off-peak windows whether you are home, asleep, or at work. That is the beauty of pre-heating — the warmth is waiting for you.

What happens during a power cut or smart meter outage?

If your smart meter stops communicating, Octopus bills you on estimated usage until the issue is resolved. They typically use your historical usage pattern to estimate fairly. Contact them promptly if your meter has issues.

Is Cosy Octopus cheaper than Economy 7?

Almost always, yes. Cosy offers more off-peak hours (9 vs 7), multiple windows throughout the day, and a lower premium on the daytime rate. For heat pump owners, Cosy is the better choice. See our Economy 7 compatibility guide for more detail.

Can I run my heat pump continuously on Cosy?

You can, but you will not maximise your savings. Running continuously means the heat pump operates during peak and standard-rate periods. For best results, schedule intensive heating during off-peak windows and let the house coast during expensive periods.

How long does it take to switch to Cosy?

If you are already an Octopus customer with a smart meter, switching to Cosy takes a few days. If you are coming from another supplier, the switch takes 2-3 weeks. If you also need a smart meter installed, allow 4-6 weeks in total.