The Short Answer
If you're fitting a heat pump and solar, we'd leave the battery out unless a time-of-use tariff can charge it cheaply overnight: on our model it adds only about £195 a year.
On our model, a 3-bed gas home on a £950 heating bill that adds a heat pump and 5kWp of solar saves about £1,164 a year against carrying on with gas and grid electricity, on a heat pump tariff with the gas supply disconnected. After the £7,500 grant in England and Wales, the extra over a new boiler pays back in about 9 years.
Estimate Your Combined Saving
The savings and paybacks above and below all assume a heat pump tariff (our 20p blend), today's prices held flat, and that you have the gas supply disconnected and stop paying its £108 a year standing charge.
Add a 10 kWh battery and the same home saves about £1,360 a year. That costs about £19,400 after the £7,500 Boiler Upgrade Scheme grant in England and Wales. Against the £2,750 you'd spend on a new boiler anyway (our estimate), the extra pays back in about 12 years. The heat pump alone saves about £407 and pays back in about 5. That's a bigger saving and a quicker payback than the £300 to £320 a year and 6 to 7 years in our heat pump guides, because those keep the gas connection and its standing charge. Put your own home in below.
1. What heats your home today?
Pick whichever your main heating uses.
Add up last year's bills, or use the typical figure for your home below.
3. What size is your home?
We use this to size both the heat pump and the solar array.
4. Which combo are you considering?
Solar pairs well with a heat pump because a heat pump runs on electricity, which is what panels make.
Your estimated saving
£1,360a year
Over 15 years that's around £20,396 off your energy bills at today's prices held flat. The battery and the solar inverter may need replacing within that time.
Heating saving
£553 / year
Heat pump replaces fuel bill
Solar used by the rest of the house
£596 / year
Solar powers fridge, lights, etc.
SEG export income
£211 / year
Selling spare solar to grid
What about the upfront cost?
- Heat pump install (6 to 8kW)
- £12,200
- Solar panels (5 kWp, 0% VAT)
- £8,200
- 10 kWh battery (0% VAT)
- £6,500
- Less Boiler Upgrade Scheme grant
- -£7,500
- You pay
- £19,400
If your boiler needs replacing anyway, the combo costs about £16,650 more upfront than a like-for-like boiler swap, earned back in roughly 12.2 years from running cost savings.
Like the look of £1,360 a year?
These are estimates. The only way to know your real saving is a free quote from MCS-certified installers. Takes about 60 seconds, no obligation.
How we worked this out
Energy prices: Ofgem price cap for 1 October to 31 December 2026 (Direct Debit, GB average): gas 7.97p/kWh, electricity 26.32p/kWh. For gas, the saving includes the £108 a year standing charge, which you only stop paying if you have the gas supply disconnected (no gas hob). There is no VAT on domestic electricity from 1 October 2026 to 31 March 2027; the gas figure includes 5% VAT. Heat pump tariff blended at 20p/kWh, an estimate rather than a quoted rate. Heating oil 11.31p/kWh; LPG at the price you enter (we start from 75p a litre, our estimate).
Heat pump efficiency: SCOP of 3.5, our standard figure. The systems on heatpumpmonitor.org average higher, but they're a self-selected group whose owners monitor them closely.
Solar: 950 kWh per kWp per year (south-facing, central England). The share used at home is the government's SAP 10.2 self-use formula for the array against the whole home's use, heat pump included, with a 10 kWh battery taken as 8kWh usable. The heat pump's use is spread over the year by heating degree days, so mostly in winter, which leaves out its summer hot water and undercounts solar a little. Of the self-consumed kWh, the heat pump's share is the extra its demand adds on the same formula (for a 3-bed, about 430 kWh with panels or 730 kWh with the battery); the rest powers the rest of the household, valued at the cap rate (our simplification: we don't model the rest of the household moving to the heat pump tariff). Spare solar exports at 12p/kWh, Octopus's Outgoing rate (variable, and only for Octopus supply customers on certain import tariffs).
Install costs: Heat pump about £11,500 to £13,900 by home size (median of real installs, DESNZ Boiler Upgrade Scheme statistics). Solar panels £6,600 to £9,900 by system size (DESNZ mean for home installs, the top of the range in our solar costs guide), 0% VAT until March 2027. Battery £6,500, the middle of the Energy Saving Trust's range for battery storage (it gives no size; the 10 kWh is our assumption). The £7,500 grant is the Boiler Upgrade Scheme (gov.uk) for England and Wales, plus £1,500 for oil or LPG homes with no mains gas until March 2027. Scotland has Home Energy Scotland's grant and loan instead; Northern Ireland has no grant open to every household (NISEP schemes fund heating for lower incomes).
Estimates only. Your actual saving depends on roof orientation/shading, installer quotes, your home's heat loss, and your electricity tariff. Always get an MCS heat loss survey and a roof survey for accurate figures.
Why They're Worth More Together
A heat pump runs on electricity, which is what panels make, and it gives them a big load to run in daylight, especially for hot water. Every kWh of solar you use yourself saves buying it: at 26.32p for the rest of the house, and at the 20p heat pump tariff for what the heat pump uses, since our figures put the heat pump on that tariff. Every kWh you export earns 12p on Octopus's Outgoing tariff (a variable rate, only for Octopus supply customers on certain import tariffs). Solar makes most in summer and a heat pump uses most in winter, so most of the overlap is in spring, autumn and summer hot water.
Our model assumes 950 kWh a year per kWp (south-facing, central England). It takes the share of solar used at home from the government's SAP 10.2 self-use formula, against the whole home's use, heat pump included. For a 3-bed with 5kWp and a heat pump, that's about 32% without a battery and 63% with one (8 kWh usable). The heat pump's use is spread by heating degree days, so mostly in winter. The heat pump's own share is the extra its demand adds on the same formula: about 430 kWh of solar a year without a battery and 730 kWh with one.
What Each Home Size Costs
| Home | Heat pump | Solar | Heat pump + solar + battery, after the grant |
|---|---|---|---|
| 1 to 2 bed flat or terrace | 4kW band, £11,500 | 4kWp, £6,600 | £17,100 |
| 3 bed semi or terrace | 6kW band, £12,200 | 5kWp, £8,200 | £19,400 |
| 4 bed or more | 10kW band, £13,900 | 6kWp, £9,900 | £22,800 |
Heat pumps at DESNZ's median for the size band, solar at DESNZ's mean for home installs (the top of the range in our solar costs guide), a battery at the middle of the Energy Saving Trust's range (£6,500; it gives no size, and the 10 kWh is our assumption), less the £7,500 grant. Heat pumps, solar panels and batteries installed in homes are 0% VAT until 31 March 2027 and 5% from 1 April 2027. Our battery guide covers whether the battery pays.
The Boiler Upgrade Scheme is for England and Wales, and oil or LPG homes with no mains gas get £1,500 more until March 2027. In Scotland, Home Energy Scotland offers up to £7,500 towards a heat pump (£9,000 for rural and island homes) plus an optional interest-free loan of up to £7,500 (Scotland heat pump grants). Northern Ireland has no grant open to every household, but NISEP schemes fund heating for lower incomes (Northern Ireland heat pump grants). The price cap rates we use are for England, Scotland and Wales.
Heat Pump First or Solar First?
If you're doing both within a year, we'd usually do the heat pump first. A season of use tells you its real electricity demand, which helps size the solar, and the heat pump is the bigger, messier job inside the house. Solar first makes sense if the roof needs work (do the panels on the same scaffold) or if your boiler has years left and you want to start saving now. Either way, ask the solar installer whether the inverter can take a battery later.
What You Don't Need
- A solar diverter on top of a heat pump, in our view, if the heat pump is already set to heat the hot water cylinder in the day.
- A battery on payback alone: on our figures it adds about £195 a year here, so it wouldn't earn back its £6,500 within its life. A time-of-use tariff that charges it cheaply overnight can change that.
Tariffs Matter
Our headline figures assume a heat pump tariff at a 20p blend (our estimate). On the 26.32p cap rate, the electricity you still buy for the heat pump costs about 32% more. Our heat pump tariff guide compares them, and our heat pump costs and solar costs guides have the detail.
Quote solar and a heat pump together
Installers who fit both can size the system as one job and tell you which to do first. Get free quotes from MCS-certified installers in 60 seconds.
Frequently Asked Questions
Optimise Your Solar + Heat Pump System
Getting the most from solar and a heat pump together means monitoring generation and controlling when your heating runs.
OWON WiFi Smart Energy Monitor
£50.39Shows how much electricity your home, or your heat pump on its own circuit, is using in real time.
WiFi + 3x CT clampsFind on Amazon
tado Smart Thermostat Starter Kit V3+
Check priceA well-liked app. It's tado's older range: tado says its newer X products, including the Heat Pump Optimizer X, don't work with V3+.
OpenTherm (boilers)Find on Amazon
Solar Panel Cleaning Kit with Extension Pole
£42.57A soft brush on a telescopic pole, for rinsing panels you can reach safely from the ground. Most rooftop panels are cleaned well enough by rain.
6m telescopic poleFind on AmazonAs an Amazon Associate we earn from qualifying purchases. Prices and stock are checked against Amazon every few hours and may have changed since.
