Heat pumps & solar panels: how they work together

If you like the idea of solar panels, chances are you’ll be thinking of adding a heat pump too – after all, you can run it on the electricity you generate with your panels.

And with Sunsave Plus offering solar panels for no upfront cost and government grants reducing the price of heat pumps, now is an excellent time to make the switch.

In this guide, we’ll explain how using a heat pump with solar panels works, how many panels you’ll need, and which properties are suitable.

If you would like to see the savings you could get from a solar & battery system, answer a few questions below and we’ll provide an estimate.

Can you power a heat pump with solar panels?

You can certainly power a heat pump with solar panels; heat pumps are powered by electricity, and solar panels continually produce free electricity.

In fact, it’s one of the best ways to lower your heating bills at the same time as reducing your electricity bills.

You can't expect to cover 100% of your heat pump's electricity needs with solar panels, but you can still slash your bills by increasing your self-consumption – that is, how much of your solar electricity goes towards powering your property, instead of being sent to the grid.

Heat pump sales are growing, with more than 200,000 now installed in the UK – and over half of those installations have taken place since the start of 2021.

A heat pump will usually increase the average three-bedroom household’s annual electricity usage by around 3,200kWh (kilowatt-hours) per year.

This will roughly double your total electricity consumption and raise your bills – unless you get solar panels, which can provide you with plenty of free electricity, all year round.

How does it work?

Like a gas boiler, your heat pump will stay on at all times, but will only run – and use substantial amounts of electricity – when it’s needed.

So whenever your property drops below the preferred temperature you’ve set – either according to your thermostat or thermostatic radiator valves – your heat pump will start running.

When this happens during the day, your solar panels will at least partly power your heat pump.

The solar electricity your system produces is sent to power as many electric appliances running in your home as possible. There’s no hierarchy of needs or way of telling which devices receive this green electricity.

So if your solar panels produce 0.7kWh of electricity over an hour, and you use 0.7kWh or less in that hour, your heat pump’s energy consumption will be 100% solar over that time.

If you consume 1kWh in that hour, your entire home’s electricity usage will be 70% solar – including your heat pump.

Adding a solar battery to your system will enable you to run your heat pump – and other home appliances – with solar electricity more of the time, which will cut your energy bills further.

There's no such thing as a solar-compatible heat pump or a non-solar-compatible heat pump – they all use solar electricity in the same way.

This is for the best, since your heat pump will almost certainly need to use grid electricity at various times.

How many solar panels do you need to power a heat pump?

Any size of solar & battery system will help to reduce the cost of powering your heat pump.

A typical three-bedroom home will need a 8.2kWp system to run a heat pump for most of the year – which you can do by getting 19 solar panels with 430-watt peak ratings – but a smaller system will still save you a significant amount on your electricity bills.

A heat pump with an average efficiency rating of around 350% – that is, one that produces three and a half times as much energy as the electricity it takes in – will need around 3,200kWh (kilowatt-hours) per year to heat the average three-bedroom household.

Since the same household needs 3,400kWh of electricity per year to power its other appliances, it requires a total of 6,600kWh, which in the UK can typically be achieved with 19 panels.

Getting a system this size will cut your heating bill significantly, especially if you also get a storage battery. This will ensure that even after the sun goes down, you can use solar electricity to heat your home – shrinking your bills further.

No realistic domestic setup will be fully sufficient in winter, when solar panels generate less electricity – around 11% of their annual output – right as the thermometer drops and heating usage rises. This is where the grid smoothly comes in to provide backup.

During the summer however, your panels are very likely to produce excess electricity, which you can sell to the grid via a solar export tariff.

So even though you’ll need to rely on the grid to provide some electricity for your heat pump, you can still save hundreds of pounds per year with a solar & battery system.

How many solar panels you need to power your heat pump alongside your home’s other appliances will ultimately depend on where you live, how much electricity you consume, and when you need it.

A heat pump will increase the amount of electricity your household requires, so you’ll need a larger solar panel system if you want to generate most of the electricity you use – but any size system will help cut your bills.

Is a solar battery necessary for a heat pump?

A solar battery is the best way to ensure your solar panels supply as much electricity to your heat pump as possible.

During winter, spring, and autumn, you can fill up your battery with solar electricity in the daytime, then use this stored energy to heat your household when it gets dark.

In the summer you won’t need your heat pump as much, so after the sun sets, you can sell the electricity in your battery to the grid, through one of the best export tariffs.

As a heat pump will significantly increase your electricity usage, it makes sense to get a slightly bigger battery, to allow you to reduce your bills by using as much solar electricity as possible.

How much does a heat pump with solar panels cost?

A heat pump with a solar & battery system that can power your home’s electricity and heating for most of the year would usually cost the average household £28,000 – but you can reduce this to £5,000 upfront with the Boiler Upgrade Scheme and Sunsave Plus.

Buying a heat pump and getting it installed typically costs around £12,500, according to the Microgeneration Certification Scheme (MCS), but the government’s Boiler Upgrade Scheme can cut this amount to £5,000.

If you get an 8.2kWp solar panel system with a 5.2kWh battery – which should ensure most of the electricity you use comes from your solar panels – this would usually cost you around £15,500.

If you sign up to Sunsave Plus though, you can get this system with no upfront cost.

You’ll also receive the Sunsave Guarantee, which includes 20 years of 24/7 monitoring and maintenance, free battery and inverter replacements, and getting your system insured by Aviva.

How much does a heat pump cost to run with solar?

Running a heat pump with a solar & battery system will cost the typical three-bedroom household £220 per year, for a saving of £564.

This is 72% less than the cost of powering a heat pump with grid electricity alone, which is £784 per year for the average home, using the October 2024 price cap.

We’ve assumed your heat pump will be roughly 350% efficient, and that you’ll consume around 3,200kWh of electricity for heating per year, which follows Ofgem’s averages.

We’ve also assumed that your system will export one-third of the electricity it produces, and that you’ll split the remaining electricity equally across your heat pump and the rest of your home.

Powering the rest of your household’s appliances with solar energy will save you another £564, on average – and your exports should earn you hundreds of pounds too, depending on which tariff you pick.

How much your household will save also hinges on factors including your location, the size of your solar & battery system, and the amount of electricity and heating your home requires.

Is your home suitable for a heat pump and solar panels?

Most homes in the UK are suitable for a heat pump and solar panels.

Heat pumps can be installed in all property types – from flats to detached houses – and in homes from any architectural era, according to the government-funded Electrification of Heat project.

That means your property’s suitability will instead come down to whether you have a good level of insulation, and enough space for the different components. You’ll need room outside for the external unit, and space inside to fit a hot water cylinder.

Ideally, you’d also have underfloor heating or large radiators, but it’s not essential.

To be suitable for solar panels, you’ll just need to own a suitable roof that’s at least mostly unshaded, faces south, east, or west (although north-east and north-west will sometimes be sufficient), and can support the weight of panels – which most can.

What’s the best export tariff to use with a heat pump and solar panels?

The best export tariff to use with a heat pump and a solar & battery system is often either Intelligent Octopus Flux or Cosy Octopus.

If your heat pump is 5.2kW or larger, Intelligent Octopus Flux will likely suit you best, according to our calculations.

On this tariff, you can store the solar electricity your panels produce during off-peak periods, then during the 4-7pm peak time, you can either sell it or use it to power your heat pump.

If you have a smaller heat pump, you’ll probably want to sign up for Cosy Octopus, which offers three off-peak periods – 4-7am, 1-4pm, and 10pm-12am – when you can heat your home with cheap grid electricity.

And a peak period from 4pm to 7pm gives you a time to sell your solar electricity to the grid at an extremely generous rate.

You’d combine this tariff with Outgoing Octopus, to get the best return on any solar electricity you export to the grid.

However, you need to consider a range of factors before deciding on the best tariff for your household.

At Sunsave, we’ll consider your individual circumstances before making a recommendation.

What if you have an electric car as well?

Most households with solar panels, a heat pump, and an electric car should choose Intelligent Octopus Go.

This tariff offers you the chance to charge your vehicle for just 7p per kWh, at any time of day – an incredibly low rate.

You can use this same rate for your whole home between 11:30pm and 5:30am, which you can use to power your heat pump during the coldest hours of the night.

This is an especially helpful tariff for you if your household uses more electricity than most, as you can rely on your solar & battery system to keep the lights on during the day, then take advantage of cheap import rates when it’s time to power your EV and heat pump.

However, if your electricity usage is relatively low aside from your electric car and heat pump, you may want to pick Intelligent Octopus Flux instead.

In either case, you’d also sign up to Outgoing Octopus to get paid well for the excess solar electricity you send to the grid.

As ever though, your ideal tariff will depend on your household’s individual circumstances.

Next steps

The best way to run a heat pump is with free, green electricity produced by your own solar panels.

You can cut your energy bills by hundreds of pounds per year, and take advantage of tariffs that reward you for using your heat pump and solar electricity in certain ways.

With government grants like the Boiler Upgrade Scheme making heat pumps affordable and Sunsave Plus providing a solar & battery system at no upfront cost, this is a great time to jump on board.

If you’re interested in how much you could save with a solar & battery system, just answer a few quick questions below and we'll generate an estimate for you.

Heat pumps with solar panels: FAQs