Heat Pump with Solar Panels and Battery: The Ultimate Setup

Introduction

A heat pump, solar panels and a home battery are three separate technologies, but together they form the closest thing a UK home can get to an integrated, low-carbon energy system. The heat pump turns electricity into heat at three or four times the efficiency of a gas boiler. The solar panels produce some of that electricity for free. The battery stores the surplus so you use it when you actually need it, rather than exporting it cheaply to the grid.

The appeal is obvious. The reality is more nuanced, and most articles gloss over the awkward bit: a UK heat pump uses most of its electricity in winter, exactly when your solar panels produce the least. Get the sizing and the tariff wrong and the battery sits half empty for five months of the year while you congratulate yourself on a system that barely moves the needle.

This guide gives you the honest version. We will work through real 2026 costs, how to size each component for each other rather than in isolation, the smart tariffs that do most of the financial heavy lifting, and four worked scenarios so you can see where this setup pays and where it does not. Throughout, the numbers use current Ofgem rates and published efficiency figures rather than best-case marketing claims.

If you are still deciding the order of installation, our guide on whether to fit a heat pump or solar panels first is the natural companion to this article.

How the Three Technologies Actually Work Together

Before the money, the mechanics. Each component does one job, and the value comes from how the jobs overlap.

Solar panels convert daylight into electricity. A typical 4 kW system on a UK roof generates roughly 3,400 to 4,000 kWh per year, but the output is heavily skewed towards the summer. A 4 kW array might produce 500 kWh in June and barely 90 kWh in December.

The heat pump consumes electricity to move heat into your home. A well-designed air source system for a three-bedroom house uses around 4,000 kWh of electricity per year, with consumption skewed the opposite way to solar: most of it falls between November and February.

The battery bridges the timing gap within a day. It stores surplus solar generated at midday so you can run appliances, hot water and some heating in the evening. Crucially, it also lets you buy cheap off-peak grid electricity overnight on a smart tariff and discharge it during expensive peak hours, whether or not the sun is shining.

The seasonal mismatch is the central fact of UK solar plus heat pump systems. In summer your panels can comfortably cover the heat pump's modest hot water demand and most household electricity, often exporting a surplus. In deep winter the panels contribute a small fraction of what the heat pump needs, and the battery's main role shifts from storing solar to time-shifting cheap grid power. A realistic expectation is that solar directly covers 15 to 30 per cent of a heat pump's annual electricity, rising with a larger array and a battery, never reaching anywhere near 100 per cent without seasonal storage that does not yet exist affordably for homes.

Understanding the heat pump's efficiency helps here. The ratio of heat delivered to electricity used is the Coefficient of Performance, and the seasonal average is the SCOP. Our explainer on heat pump COP covers why a SCOP of 3.5 means every kWh of solar electricity you self-consume effectively delivers 3.5 kWh of heat.

Is a Heat Pump with Solar and Battery Worth It? A Data-Driven Answer

The blunt answer: the heat pump and the solar plus battery system are two separate investments that happen to complement each other, and they should be judged that way.

The heat pump's value is almost entirely about replacing a fossil fuel boiler. With the £7,500 Boiler Upgrade Scheme grant, an air source heat pump replacing an oil or LPG boiler is straightforwardly cheaper to run and to own. Replacing mains gas is closer to break-even on a standard tariff and clearly positive on a smart tariff. The full picture is in our heat pump running costs analysis.

The solar plus battery's value is about reducing the price you pay for electricity. It does not care whether that electricity feeds a heat pump, a kettle or an electric car. What the heat pump adds is a large, flexible, year-round electrical load that gives a battery far more to do, which improves the battery's payback compared with a home that only has lighting and appliances.

Put simply: the heat pump makes the solar plus battery work harder, and the solar plus battery shaves the heat pump's running cost. Together they are more than the sum of their parts, but neither rescues a poorly sized or badly tariffed version of the other.

A realistic headline for a well-insulated three-bedroom semi with a 5 kW heat pump, a 4 kW solar array and a 10 kWh battery on a smart tariff: total heating and hot water running cost of roughly £350 to £500 per year, against £900 to £1,200 for the gas boiler it replaced. The combined upfront cost after the BUS grant typically lands between £13,000 and £18,000.

How to Correctly Size Solar and Battery for a Heat Pump

This is where most systems are won or lost. Sizing each part for the others, rather than buying the biggest of everything, is what separates a sensible setup from an expensive one.

Sizing the solar array

The instinct to maximise roof coverage is reasonable, because solar is the cheapest of the three technologies per unit of value once installed. As a rule of thumb for a heat pump home:

Heat pump size	Suggested solar array	Annual solar output (typical)
5 kW (small or well-insulated home)	3.5 to 4 kW	3,000 to 3,400 kWh
8 kW (three-bed semi)	4 to 6 kW	3,400 to 5,100 kWh
12 kW (larger or less insulated home)	6 to 8 kW	5,100 to 6,800 kWh

South-facing roofs maximise output, but east and west splits are fine and actually spread generation across the day, which suits self-consumption. The limiting factor is usually roof area and budget rather than matching the heat pump precisely, because the seasonal mismatch means you can never size solar to cover winter heating anyway.

Sizing the battery

Battery sizing is more subtle than capacity alone. Two numbers matter:

Usable capacity (kWh) determines how much energy you can store. For a heat pump home, 8 to 12 kWh is the sweet spot for a typical three-bedroom house. Going much larger rarely pays unless you have a large array or an electric car.
Continuous discharge power (kW) determines how fast you can draw energy out. This is the figure installers and marketing routinely ignore. A heat pump can draw 1.5 to 3 kW while running, and your home's other loads stack on top. A battery rated for only 2.5 kW continuous discharge will hit its ceiling on a cold evening and pull the shortfall from the grid at peak rates, quietly undermining the saving you paid for.

For a heat pump home, look for a battery offering at least 3.6 kW, and ideally 5 kW, of continuous discharge. This matters far more in winter than capacity does.

Component	Recommended for a 3-bed semi
Solar array	4 to 5 kW
Battery usable capacity	10 kWh
Battery continuous discharge	3.6 to 5 kW
Inverter	Hybrid, sized to handle future expansion

A hybrid inverter is strongly recommended because it manages solar, battery and grid in one unit and gives you the controls needed to exploit smart tariffs. Choosing one with headroom means you can add battery capacity later without replacing the inverter.

The Real Costs: A Full System Breakdown for 2026

Honest costing means separating the components and applying the grant only where it belongs, to the heat pump.

System component	Typical cost (before grant)	Grant or relief	Net cost
Air source heat pump (installed)	£11,000 to £14,000	minus £7,500 BUS grant	£3,500 to £6,500
Solar PV array (4 to 5 kW, installed)	£6,000 to £8,500	0% VAT until March 2027	£6,000 to £8,500
Battery storage (10 kWh, installed)	£4,000 to £7,000	0% VAT until March 2027	£4,000 to £7,000
Combined total	£21,000 to £29,500	minus £7,500	£13,500 to £22,000

A few points that the glossy bundle adverts skip over:

The BUS grant applies only to the heat pump. There is no cash grant for solar or batteries in England, though the 0% VAT relief on solar and storage (in place until 31 March 2027) saves you the 20% you would otherwise pay.
Installing all three at the same time usually reduces the total versus doing them separately, because you share scaffolding, electrical works and a single fuse box upgrade. A consumer unit or supply upgrade to handle the combined load can cost £500 to £1,500 and is easy to forget in budgeting.
Bundled "all-in-one" packages can be convenient but are not automatically cheaper. Always price the components separately from at least one MCS-certified installer as a sanity check, because the heat pump and the solar plus battery are often best fitted by specialists in each.

For a deeper breakdown of the heat pump element alone, our complete heat pump cost guide walks through every line item.

Maximising Savings: A Guide to Smart Tariffs

The single biggest lever on running cost is not the size of your solar array. It is the electricity tariff. A heat pump with solar and a battery on a poorly chosen flat tariff will save a fraction of what the same hardware saves on a tariff designed for flexible loads.

The mechanism is simple. A battery lets you buy electricity when it is cheap and use it when it is expensive. Modern time-of-use tariffs create a wide gap between off-peak and peak prices, and your battery and heat pump exploit that gap every single day, all year round, regardless of the weather.

Tariff (illustrative 2026 rates)	Off-peak rate	Peak rate	Best suited to
Cosy Octopus	around 12p/kWh	around 26p/kWh	Heat pumps, with two daytime cheap windows
Intelligent Octopus Go	around 7 to 12p/kWh	around 28p/kWh	Battery and EV charging overnight
Standard Ofgem capped tariff	flat, around 24.5p/kWh	flat	A baseline, not a strategy

The Cosy Octopus tariff is built around heat pumps, with cheap windows in the early morning and early afternoon that let you pre-heat the home and the hot water cylinder when power is cheapest. Intelligent Octopus Go offers a very low overnight rate ideal for filling the battery before a winter day. Many heat pump households run a hybrid strategy: charge the battery overnight at the cheapest rate, top it up from solar during the day, and discharge it through the expensive evening peak.

The practical effect is that a battery charged at 12p and discharged to displace 26p peak power earns a clear margin on every stored kWh, while your heat pump runs its heaviest demand inside the cheap windows. This is what pulls a heat pump's effective electricity price down towards 14 to 18p per kWh on a blended basis, well below the flat capped rate. The Energy Saving Trust's guidance on air source heat pumps confirms that tariff choice and controls, not raw hardware, drive most of the running-cost difference between households.

Note that smart tariffs change regularly, so treat the rates above as illustrative and check current offers with your supplier before committing.

The Boiler Upgrade Scheme and Other Grants

The Boiler Upgrade Scheme remains the cornerstone incentive for the heat pump part of the setup.

£7,500 off an air source heat pump.
£7,500 off a ground source or water source heat pump.
The grant is claimed by your installer, who must be MCS-certified, and is deducted from your invoice. You pay the balance.

Eligibility is set out on the official GOV.UK Boiler Upgrade Scheme page. In short, the property must be in England or Wales, you must be replacing a fossil fuel system, and you must hold a valid EPC with no outstanding recommendations for loft or cavity wall insulation. That insulation condition is the one that catches people out, so check your EPC before you commit. Our complete Boiler Upgrade Scheme guide explains the process step by step.

For the solar and battery, the support is the 0% VAT relief running until 31 March 2027, which applies to the supply and installation of qualifying energy-saving materials in residential property, as confirmed by Ofgem and HMRC guidance. After that date the rate is currently scheduled to return to 5%, so bringing an installation forward can be worth a meaningful sum on a £12,000 solar and battery spend.

Scotland and Wales run their own routes. Home Energy Scotland offers grants and interest-free loans, and the Welsh Nest scheme supports eligible households, which we cover in our regional guides for Scotland and Wales.

Case Study: From Gas Boiler to a Near Self-Powered Home

Consider a three-bedroom 1990s semi-detached house, EPC rating C, with a 14-year-old gas boiler nearing replacement. The owners installed the full setup in spring 2026.

What they fitted:

5 kW air source heat pump, replacing the gas boiler.
4.5 kW solar array (south and west split).
10 kWh battery with 5 kW continuous discharge.
Hybrid inverter, on the Cosy Octopus tariff.

The numbers:

Item	Figure
Heat pump installed	£12,500
BUS grant	minus £7,500
Solar and battery installed	£11,500
Net upfront cost	£16,500
Old gas boiler running cost	around £1,050 per year
New combined heating and hot water cost	around £420 per year
Annual running-cost saving	around £630 per year

The solar array directly supplied roughly a quarter of the heat pump's annual electricity, concentrated in spring and autumn. The battery's larger contribution came from storing cheap overnight power and discharging it through the evening peak, which is why the running cost fell so far below a heat pump on a flat tariff. In summer the household frequently ran on near-zero grid import for days at a time and exported a surplus under the Smart Export Guarantee. In December and January the solar contribution was negligible and the savings came almost entirely from the tariff arbitrage that the battery and heat pump controls made possible.

The payback on the heat pump portion alone, thanks to the grant, was around eight years against a like-for-like gas boiler replacement. The solar and battery portion paid back over a longer horizon of roughly 11 to 14 years, shortened by the heat pump giving the battery far more daily work than a typical home.

Choosing the Right Components

You do not need the most expensive equipment, but a few choices materially affect how well the system performs.

Heat pump. Prioritise a unit your installer sizes correctly to your home's heat-loss survey rather than a brand badge. Correct sizing and a low flow temperature deliver a higher SCOP, which is the difference between 3,400 and 4,500 kWh of annual consumption. A modern monobloc air source unit using R32 refrigerant is the mainstream choice for most homes. If you are looking at a three-bed semi specifically, a 5 to 8 kW output is the usual range.

Solar panels. Modern monocrystalline panels at 20 to 22 per cent efficiency are standard. Total array output in kW matters more than the brand of individual panel. Make sure the array and inverter are sized to your roof and future plans rather than to a sales target.

Battery. This is where to focus attention. Confirm the usable capacity (not the nominal figure), the continuous discharge power (aim for 3.6 kW or more for a heat pump home), the round-trip efficiency (look for around 90 per cent), and the warranty (10 years and a stated cycle or throughput guarantee is the benchmark). A battery that cannot discharge fast enough to cover a running heat pump on a winter evening will silently leak savings to the grid.

Inverter and controls. A hybrid inverter that integrates solar, battery and grid, with the ability to schedule charging around your tariff windows, is what ties the system together. Without intelligent control, you own three good technologies that do not cooperate.

Common Mistakes to Avoid

Buying a huge battery to cover winter heating. It cannot. The seasonal mismatch means a domestic battery time-shifts power within a day, not across seasons. A 10 kWh battery is plenty for most homes; a 20 kWh battery rarely pays for the heating use case.
Ignoring discharge power. Capacity sells batteries, but continuous discharge power is what lets the battery actually run a heat pump on a cold evening.
Staying on a flat tariff. This wastes the largest single saving the system can deliver. The battery and heat pump exist to exploit time-of-use pricing.
Skipping the heat-loss survey. An oversized or badly commissioned heat pump runs at a poor SCOP, and no amount of solar fixes a heat pump that uses more electricity than it should.
Forgetting the supply upgrade. Three flexible loads on one home can require a consumer unit or supply review. Budget for it from the start.

Frequently Asked Questions

Will my solar panels power my heat pump in winter?

Only partially. A UK solar array produces the bulk of its electricity between April and September, while a heat pump uses most of its electricity between November and February. In deep winter, solar might cover a small fraction of the heat pump's demand. The battery's winter role shifts from storing solar to time-shifting cheap off-peak grid electricity, which is where most of the cold-season saving comes from.

How big a battery do I need for a heat pump?

For a typical three-bedroom home, 8 to 12 kWh of usable capacity is the sweet spot. Equally important is the continuous discharge power: aim for at least 3.6 kW, ideally 5 kW, so the battery can supply a running heat pump plus household loads on a winter evening without pulling expensive power from the grid.

Does the £7,500 BUS grant cover solar panels or the battery?

No. The Boiler Upgrade Scheme applies only to the heat pump. Solar panels and batteries instead benefit from 0% VAT until 31 March 2027, which saves the 20% you would otherwise pay on the supply and installation.

Is it cheaper to install everything at once or in stages?

Installing together usually lowers the combined cost because you share scaffolding, electrical works and any supply upgrade, and you avoid disrupting the property twice. If budget forces a phased approach, size the solar and inverter for the eventual heat pump load and choose a hybrid inverter with room to add a battery later. Our guide on which to install first covers the trade-offs.

What annual saving is realistic from the full setup?

For a well-insulated three-bedroom home on a heat-pump-friendly smart tariff, expect total heating and hot water running costs of roughly £350 to £500 per year, against £900 to £1,200 for the gas boiler replaced. The exact figure depends heavily on insulation, the SCOP achieved, and how well you exploit your tariff.

Sources

GOV.UK, "Apply for the Boiler Upgrade Scheme": https://www.gov.uk/apply-boiler-upgrade-scheme
Ofgem, "Check if the energy price cap affects you": https://www.ofgem.gov.uk/check-if-energy-price-cap-affects-you
Energy Saving Trust, "Air source heat pumps": https://energysavingtrust.org.uk/advice/air-source-heat-pumps/
Energy Saving Trust, "Solar panels": https://energysavingtrust.org.uk/advice/solar-panels/
MCS, "Find an installer": https://mcscertified.com/find-an-installer/

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