Home Battery With a Heat Pump: What It Can and Cannot Do
- Heat pumps use the most electricity in winter, when solar output is lowest.
- A battery helps mainly by storing cheaper off-peak or surplus electricity for later.
- Hot water tanks and the building itself can also store heat, often more cheaply.
- Backup power rarely covers a heat pump unless the battery output is sized for it.
- Check your own meter data before sizing anything.
A home battery can move some of a heat pump's electricity use to cheaper hours, but it cannot make up for a poorly set up house or a tariff that does not reward shifting.
The mismatch between solar and heat
Heat demand is highest in the cold months, and solar panels produce the least then. That means a battery charged by summer-style solar surplus is unlikely to carry a heat pump through winter. How much a heat pump uses varies a lot with the house, the system and the weather, so we are not putting a single figure on it. Your smart meter or bills are the right place to look.
What a battery can do in winter is charge from the grid when electricity is cheaper and release it in the evening peak, when heating demand is often high. That only pays if your tariff has a real price difference. Our article on how a home battery saves money explains the maths.
Other ways to shift heating load
Before buying a battery for a heat pump, look at stores that already exist. A hot water cylinder can be heated when power is cheap, and a well insulated house loses heat slowly, so you can pre-heat it. These can shift load without extra hardware or battery wear.
A battery is flexible, since it can serve every appliance, not just heating. But it is not always the cheapest way to move a given amount of energy. Ask an installer to compare the options on your actual usage.
Good to know
Ask your installer how the battery decides when to charge. A heat pump on a time-of-use tariff may need the two to be set up together.
Power cuts and heat pumps
Many home battery backup systems are designed to run selected circuits such as lighting, the fridge and the router. A heat pump can draw more power than the backup output allows, and the system also needs circulation pumps and controls to work. If heating in a power cut matters to you, ask the installer in writing whether the heat pump can be on the backed-up circuit and what capacity that needs.
We have not verified specific products for this, and a battery is not a safe replacement for emergency heating plans. Our guide to how whole-home backup works explains what backup can and cannot run.
How to decide
Begin with a clear picture of when you use electricity. Then check whether your tariff pays you to shift it, whether controls such as a smart thermostat can do part of the job, and only then size a battery. The home battery calculator can help with that last step.
If you are installing a heat pump and a battery together, ask for one quote that covers how they work as a system, including who commissions the controls.
Common questions
Do I need a home battery if I have a heat pump?
No. A heat pump works without one. A battery may help if you have cheaper electricity at certain times, but it is an add-on and not a requirement.
Will a battery power my heat pump during a power cut?
Only if the battery and wiring are set up for it and the output is large enough. Many backup systems cover selected circuits only, so ask before you buy.
Does a battery lower the cost of running a heat pump?
It can if your tariff has cheap and expensive periods and the battery is used to shift load. We cannot give a figure, because it depends on your tariff and usage.
Should I buy a bigger battery because of the heat pump?
Not automatically. Check your actual evening use first, since a larger battery that rarely fills or empties adds cost without adding benefit.
Related guides
Want to know which battery size fits your home?
Use our free calculator to get a size, savings and payback estimate.