No. A typical air-source or ground-source heat pump stops working during a power cut because it needs electricity to run its outdoor unit, controls and water pumps. It can keep heating only if a compatible backup supply has been designed and installed to operate the system during an outage. The UK Government’s power-cut guidance also notes that heat pumps and gas boilers will not work without electricity.
A power cut does not make a heat pump uniquely vulnerable: most central heating depends on electricity for controls or circulation. A warm radiator, hot-water cylinder and the building itself may retain some heat for a while, but that is stored warmth, not active heating. How quickly the home cools depends on the weather, the building and how it is used.
What happens to a heat pump in a power cut?
When the electricity supply stops, the heat pump cannot collect and move heat around the home. The compressor, controller and circulation pumps need power. Any electric immersion heater or other backup heater in the system needs power too.
| Home energy setup | Will it heat the home during a power cut? | What to check |
|---|---|---|
| Heat pump connected to the mains | No | It stops until power returns. |
| Solar panels without backup equipment | Usually no | Most grid-connected systems stop supplying the home during an outage. |
| Battery with backup capability | Possibly | The system must be designed and configured to operate independently of the grid, with enough output for the heat pump. |
| Generator | Possibly | It must be suitable for the heat pump and connected safely through a designed arrangement. |
| Heat pump and boiler hybrid | Do not assume so | Check whether the boiler and its controls can operate without mains electricity. |
If you have a hybrid system, the boiler is not automatically a fallback. Boilers commonly need electricity for their controls and pumps, and government power-cut advice says they will not work without power.
Can solar panels or a home battery run a heat pump?
Solar panels do not normally power a home during an outage. They usually shut off when the grid fails unless the installation includes equipment designed to operate independently. A standard home battery also does not necessarily provide backup power. The Energy Saving Trust’s solar power guidance explains that the system needs the right additional equipment and configuration.
If you want a battery to run your heat pump, ask your installer to confirm that the inverter can support the system and that the backup arrangement includes the necessary heat-pump circuits, controls and pumps. The battery’s power output, measured in kilowatts, affects what can run at once. Its stored energy, measured in kilowatt-hours, and conversion losses affect how long it can run.
A battery that can run lights and charge phones may not be able to run a heat pump. Ask the heat-pump installer for the system’s electrical requirements and have the backup system designed around those figures. Do not rely on the battery’s capacity figure alone.
Can a generator run a heat pump?
It may be possible with a generator that is suitable for the heat pump’s electrical requirements. The generator also needs a safe, properly designed connection. If the heat pump is connected to fixed household wiring, ask a qualified electrician to design and install the changeover arrangement. The IET’s generator guidance explains the need to manage the changeover between mains and generator supplies safely.
Never feed a generator into a household socket or improvise a connection to your home’s wiring. A generator can energise wiring that should be isolated from the network. Follow the generator’s instructions, and never exceed its rated load.
Run a petrol or diesel generator outdoors, at least 6 metres from doors and windows, with its exhaust facing away from the home. Do not use one in a house, garage, shed or other enclosed or partly enclosed space. Generator exhaust contains carbon monoxide, which can kill. The UK Chief Medical Officers’ power-outage advice gives the outdoor distance; the Health and Safety Executive for Northern Ireland’s generator guidance warns against using generators indoors or in partly enclosed spaces.
How to keep warm while the power is off
For a short outage, focus on keeping heat in rather than trying to power the whole heating system. The UK Chief Medical Officers advise households to:
- Gather in one room to share warmth.
- Wear several thin layers and use blankets.
- Close curtains or blinds when it gets dark.
- Close windows and doors in rooms you are not using.
- Put a towel or sheet at the bottom of doors to reduce draughts.
Keep any ventilation needed by fuel-burning appliances clear, and use only heaters designed for indoor use. Never use a barbecue, camping stove or outdoor patio heater inside the home.
If someone in your household depends on powered medical or care equipment, make an outage plan with their provider and check whether you can join the Priority Services Register. In England, Scotland and Wales, call 105 to report a power cut. In Northern Ireland, the government advises calling 03457 643643. Our home resilience checklist includes further steps for preparing your household for a power cut.
Heat pump power-cut resources
- The UK Government’s power-cut guidance explains what stops working, how to prepare, and how to report an outage in each UK nation.
- The Energy Saving Trust’s solar power fact check explains why solar panels and batteries do not automatically provide power when the grid fails.
- The UK Chief Medical Officers’ advice for a power outage covers keeping warm and safe generator use.
- The Health and Safety Executive for Northern Ireland’s generator advice covers carbon monoxide, electrical and fire risks from portable generators.
- The IET’s guidance on generators and uninterruptible power supplies discusses safe changeover between mains and standby supplies.
- The Met Office’s power-cut advice explains how to contact the electricity network operator and prepare for an outage.
