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Heat pumps & solar panels: how they work together
Here's how using a heat pump with solar panels works, and which homes are suitable.
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What's in this guide?Solar panels and heat pumps: at a glance
✂️ You can cut your heat pump bills by hundreds of pounds with solar panels
Powering your heat pump with solar panels is one of the best ways to lower your heating bills at the same time as reducing your electricity bills.
You shouldn’t expect to cover 100% of your heat pump's electricity needs with solar panels, but you can still save hundreds of pounds per year.
🏠 More than 200,000 households now have a heat pump
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.
This surge in demand is mirrored in the increasing popularity of electric vehicles, both of which are part of the UK electrifying its heating and transport networks in the coming years.
👍 The majority of UK homes are 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 suitability will instead come down to whether you have a good level of insulation, and enough space for the different components.
💷 Use a solar export tariff that favours heat pump owners to save even more
If you have a large heat pump, Intelligent Octopus Flux will help you store the solar electricity your panels produce during off-peak periods, then either sell it or use it to power your heat pump at peak times.
If you have a smaller heat pump, Cosy Octopus is usually the best choice, as it offers two off-peak periods when you can heat your home with cheap grid electricity.
A peak period from 4pm to 7pm also gives you the opportunity to sell your solar electricity to the grid at an extremely generous rate.
🌍 Running a heat pump on solar electricity shrinks your carbon footprint
Using a heat pump with solar panels slashes your household’s carbon emissions by a total of 3.1 tonnes of CO2 per year, on average.
This would wipe out the great majority of the typical home’s carbon footprint.
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?
- Solar panels can provide a substantial amount of your heat pump’s power
- A heat pump will increase your energy bills – unless you use solar panels
- With a solar battery, you can run your heat pump on solar electricity at night
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.
🤔 Thinking of going solar? Here's why a larger system makes sense ⬇️
When you’re switching to solar, it's worth getting as large a solar & battery system as you can.
A few extra solar panels won't add much to the overall cost, but in most cases they'll have a big impact on your energy bill savings.
And for the majority of homes, a larger battery will significantly increase the value you get from your solar panels.
To understand all the key reasons in detail, check out the articles below.
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.
Verified expertIf you have solar panels and a heat pump, the best export tariff for you mostly depends on the size of your solar system. For smaller systems, you might be better off with Cosy Octopus for your imports and Octopus Outgoing for your exports. However, for larger systems, you should probably choose Intelligent Octopus Flux. At Sunsave, we’ll help you find the right tariff for your setup.
Alfie Ireland
Head of Operations & Technical at Sunsave
Alfie has worked in green tech for over a decade. During his four years at OVO, he helped develop the world’s largest domestic vehicle-to-grid trial.
How many solar panels do you need to power a heat pump?
- A 7.2kWp system is typically the most cost-effective way to power a heat pump
- A solar battery will help you use more of the electricity your panels produce
- Solar panels can help you save hundreds of pounds on your heating bills
A typical three-bedroom home will need 18 solar panels with 400-watt peak ratings to power a heat pump for most of the year, which means buying a 7.2kWp system.
This will cut your heating bill significantly, so even though you’ll need to rely on the grid to provide some electricity for your heat pump, you’ll still save hundreds of pounds per year.
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 2,700kWh of electricity per year to power its other appliances, it requires a total of 5,900kWh, which in the UK can typically be achieved with 18 panels.
However, solar panels don’t produce electricity at night, so you’ll need a solar battery to store energy that can then be used to heat your home after the sun goes down.
And this setup won’t 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 shoots up. This is where the grid smoothly comes in to provide backup.
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 – but in any case, you’ll need a drastically larger system.
The more cost-effective option is usually to generate the majority of your profits in summer, then top up your panels’ supply with grid electricity in winter.
Verified expertThe ideal number of solar panels you should get doesn’t really change depending on whether you have a heat pump - either way, it’s best to make full use of the space on your roof. Once you’ve paid the fixed costs of installation such as scaffolding and labour, it makes sense to get as many solar panels as possible.
Alfie Ireland
Head of Operations & Technical at Sunsave
Alfie has worked in green tech for over a decade. During his four years at OVO, he helped develop the world’s largest domestic vehicle-to-grid trial.
Does a solar battery help?
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.
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How much does a heat pump with solar panels cost?
A heat pump with solar panels will cost the typical household £17,500, overall.
This will get you a 7.2kWp solar panel system, for around £12,500, which is large enough to power your home’s electricity and heating for most of the year.
Buying a heat pump and getting it installed costs another £12,500 on average, according to the Microgeneration Certification Scheme (MCS) – but fortunately, the government Boiler Upgrade Scheme can reduce this price tag by £7,500.
If you want to add a solar battery at the same time, it’ll usually set you back another £2,000, for a total of £19,500.
However, if you sign up for Sunsave Plus, you won’t have to pay anything upfront for your solar & battery system, taking the overall cost down to just £5,000 for the heat pump.
You’ll also receive the Sunsave Guarantee, which means 20 years of 24/7 monitoring and maintenance, free battery and inverter replacements, and insurance against theft, damage, and fire.
Using a heat pump with solar panels slashes your household’s carbon emissions by a total of 3.1 tonnes of CO2 per year, on average.
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 £297 per year.
This is a 59% saving on the cost of powering a heat pump with grid electricity alone, which is £716 per year for the average home.
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 you’ll use 50% of your solar electricity to power the heat pump.
Of course, this doesn’t include the money you’ll save by using your solar electricity to run the rest of your household’s electrical devices, or how much you’ll earn by selling your excess solar power to the grid.
How much your household will save also depends on factors including your location, the size of your solar & battery system, and the amount of electricity and heating your home requires.
If you’re wondering how much a solar & battery system could save you, answer a few questions below and we’ll provide you with an estimate.
Are there any grants for heat pumps and solar panels?
- Electrically heated households can get free solar panels through the ECO4 scheme
- The Home Upgrade Grant can help some properties get solar panels or a heat pump
- The Boiler Upgrade Scheme offers £7,500 heat pump grants to homeowners
There are several heat pump and solar panel grants available to households in the UK.
The government’s ECO4 scheme compels large suppliers to install solar panels in electrically heated, energy-inefficient households.
If you own or privately rent a home with an Energy Performance Certificate (EPC) rating of D-G, and someone in the property receives a qualifying benefit, you may be able to get solar panels for free.
The Home Upgrade Grant can provide solar panels and a heat pump for a large discount or completely free, at your local council’s discretion – but only if you’re not connected to the gas grid.
It’s available in hundreds of local authorities all over England, for low-income households with an EPC rating of D-G.
The Boiler Upgrade Scheme is available to all homeowners in England and Wales, and allows you to get £7,500 off the cost of an air, ground, or water source heat pump.
If you live in a Scottish property you own, you may be eligible for the government’s Home Energy Scotland Grant & Loan.
This scheme doesn’t provide help with solar panels anymore (as of 6 June 2024), but does offer a £7,500 grant for a heat pump, plus an optional zero-interest loan of up to £7,500 to cover any additional costs.
And if you’re in Wales, you may be able to access the Welsh Government Warm Homes Programme, which provides free measures including heat pumps and solar panels.
To qualify, you must own or privately rent your home, have a low rating on your EPC report, and either live in a low-income household or receive a means-tested benefit.
You could also look into solar panel loans.
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.
Most homes in the UK are suitable for a heat pump and solar panels.
What’s the environmental benefit of a heat pump with solar panels?
The environmental benefit of using a heat pump with solar panels is that it reduces the average household’s carbon emissions by a massive 88%.
This would wipe out the great majority of the typical home’s carbon footprint.
Generally, your heat pump will get about 68% of its electricity from the grid, which still uses gas and coal to generate around one-third of its electricity.
This will result in 0.4 tonnes of CO2 emissions – which is a saving of 1.8 tonnes compared to the average gas boiler, according to Nesta.
With a 7.2kWp solar panel system, the average system in the UK will produce an extra 4,900kWh on top of the power needed for your heat pump – which will save an additional tonne of CO2 per year by replacing most of your grid electricity.
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.
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
Do heat pumps work well with solar panels?
Heat pumps work extremely well with solar panels.
Solar panels produce electricity whenever there’s daylight, which goes straight to powering all your electrical appliances – including your heat pump.
That means you can generate warmth with free, green electricity.
If you have solar panels and a heat pump, you can also benefit from tariffs like Cosy Octopus, which provides you with off-peak periods when you can heat your household with cheap grid electricity.
You can then export your excess solar electricity during the peak period between 4pm and 7pm to get the biggest returns.
How many solar panels do I need to run a heat pump?
You can use any number of solar panels to run a heat pump, but the more you have, the less electricity you’ll need to buy from the grid.
The most cost-effective option for a typical three-bedroom household in the UK is to install a 7.2kWp solar panel system. You could create this setup with 18 panels that each have a peak power rating of 400 watts.
But the optimum number of solar panels for running your household and heat pump will depend on a number of considerations, including your location, electricity consumption, and heating needs.
How much is a solar-assisted heat pump?
An air source heat pump costs £12,500 to buy and install, on average – though this falls to £5,000 if you use the government’s Boiler Upgrade Scheme.
This £7,500 grant is available to any homeowner in England and Wales who wants to purchase an air, ground, or water source heat pump.
All heat pumps can be solar-assisted, as solar panels generate electricity, which is what heat pumps use to turn warmth from natural resources like air, ground, and water into heat.
Is getting a heat pump with solar panels worth it?
Getting a heat pump with solar panels is worth it for the environmental benefits, and to future-proof your property as energy prices rise and a gas boiler ban looms on the horizon.
You’ll also earn plenty of savings with all the free electricity your panels generate and your heat pump will use.
You may not be enough to break even on the entire system – but this will depend on your specific setup and what exactly happens to energy prices over the coming decades.
Is a 5kW solar panel system enough to heat a house?
A 5kW solar panel system can heat a house some of the time, with the help of a heat pump.
However, a 5kW system won’t be large enough to allow you to power your heating system with exclusively solar electricity, even with a solar battery.
This is partly because you need your panels to power your other electric appliances too, and also because your system won’t generate electricity after the sun goes down.
Exactly how much electricity your solar panel system can supply to your heat pump will depend on various factors, including your electricity consumption, location in the country, and solar panel system’s output.
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Josh has written about the rapid rise of home solar for the past five years. His data-driven work has been featured in United Nations and World Health Organisation documents, as well as publications including The Eco Experts, Financial Times, The Independent, The Telegraph, The Times, and The Sun. Josh has also been interviewed as a renewables expert on BBC One’s Rip-Off Britain, ITV1’s Tonight show, and BBC Radio 4 and 5.