Solar Panels vs a Heat Pump: Which Saves a UK Home More?

It’s one of the most common questions once a household starts thinking seriously about cutting energy bills: solar panels or a heat pump — which is the better buy? The honest answer is that it’s slightly the wrong question, because the two aren’t really rivals. Solar panels cut your electricity bill and generate power. A heat pump cuts your heating bill and replaces a gas boiler. They tackle different lines on your energy account, and for a lot of UK homes the best long-term answer is both — just rarely in the same year. Here’s the maths, with 2026 numbers and the downsides stated plainly.

They don’t really compete — they cut different bills

A typical UK home’s energy spend splits into two big buckets: electricity (lights, appliances, hot water top-up, EV charging) and heating (usually a gas boiler running radiators and hot water). Those two buckets are priced completely differently and served by completely different kit.

Solar panels turn daylight into electricity. A typical 4kWp array generates around 3,400–3,800 kWh a year in the UK and shaves money off the electricity bucket — either by powering the house directly or by exporting surplus. It does almost nothing for your gas heating.

An air source heat pump does the opposite. It takes electricity and uses it to move heat into your home, delivering around three units of heat for every unit of electricity it draws (a “coefficient of performance” of roughly 3, sometimes higher). It replaces the gas boiler entirely, so it targets the heating bucket — the biggest single slice of most homes’ energy use — and takes you off fossil gas.

Because they act on different bills, comparing them head-to-head on “annual saving” is a bit like comparing a new roof to a new kitchen. The more useful question is: which bucket is costing you most, and which upgrade the sums — and grants — favour right now.

The honest comparison, side by side

	Solar panels (~4kWp)	Air source heat pump
What it does	Generates electricity from daylight	Produces heating and hot water from electricity
Which bill it cuts	Electricity	Heating (replaces a gas boiler)
Typical upfront cost	£6,000–£8,000 (0% VAT to 31 Mar 2027)	£10,000–£14,000 before grant
Main help available	0% VAT; SEG export income (~12p/kWh, as at July 2026)	£7,500 Boiler Upgrade Scheme (England & Wales, as at July 2026); 0% VAT
Typical net cost after help	£6,000–£8,000	~£3,000–£6,500 after the grant
Typical annual bill saving	£400–£700	Often modest vs a modern gas boiler; larger on a heat-pump tariff
Payback on bill savings alone	~7–12 years	Long / uncertain on bills alone; far better when it replaces a dying boiler
Carbon cut	~0.7–0.8 tonnes a year	Can more than halve your heating emissions
Best for	Homes with daytime electricity use and a decent roof	Homes coming off gas, especially with a failing boiler

All figures are 2026 ranges and would be confirmed at a proper survey — never treat any single number here as a guarantee. Solar generation assumes a south-facing, unshaded roof; heat-pump running costs assume a well-insulated, correctly-sized system.

The honest bit about heat-pump savings

This is where a lot of marketing quietly oversells. A heat pump is genuinely efficient — three-ish units of heat per unit of electricity is real. But there’s a catch that installers don’t always lead with: electricity costs roughly four times as much as gas per unit. With the Ofgem price cap at 26.11p/kWh for electricity (July–September 2026) and gas at roughly a quarter of that, the efficiency advantage and the price disadvantage largely cancel out.

The upshot is that, on a standard tariff, a heat pump’s running cost often lands close to a modern condensing gas boiler — sometimes a little less, sometimes a little more, depending on how well your home holds heat. The clearer wins come from two places: a specialist heat-pump electricity tariff (which prices the heating hours much lower), and the simple fact of getting off fossil gas and its standing charge.

So if you judge a heat pump purely on bill savings, the payback can look very long or be hard to pin down at all. That’s the honest position — and it’s why the heat-pump case rests less on fast savings and more on three other things: the £7,500 grant shrinking the upfront gap, decarbonisation, and comfort (a well-designed heat-pump system delivers steady, even warmth). Crucially, if your current boiler is old and about to need replacing anyway, the sums improve sharply, because you’re comparing the net cost against a new boiler you’d have bought regardless — not against £0.

Why solar’s savings case is clearer

Solar’s numbers are easier to stand behind, and the reason is a single lever: self-consumption. A unit of electricity you generate and use in the house avoids buying that unit from the grid at ~26p. A unit you export earns only around 12p under the Smart Export Guarantee (as at July 2026). So a self-used unit is worth roughly double an exported one — and that value survives every export-rate cut.

That’s why a typical 4kWp system saves most homes about £400–£700 a year, paying back in roughly 7–12 years on panels warrantied to keep working for 25 years or more. It’s not a spectacular return, but it’s a measurable, defensible one — you can check the working. We walk through it on the how much do solar panels save page, and you can put your own roof and usage in on the savings calculator to see the range for your home. If you want the full break-even picture — including where a battery helps and where it doesn’t — the solar panel payback page lays it out.

The contrast with heat pumps is the point: solar’s benefit is a straightforward bill saving you can model; a heat pump’s benefit is a mix of a big grant, a carbon cut, and running costs that are roughly a wash unless you’re on the right tariff.

The grant vs the tax break: how the help differs

The support available is very different in shape, and it tilts the maths.

Heat pumps benefit from the Boiler Upgrade Scheme: a £7,500 grant towards an air source heat pump for homes in England and Wales, paid through your MCS-certified installer (as at July 2026; Scotland runs its own Home Energy Scotland grant-and-loan instead). Your property usually needs a valid EPC with no outstanding insulation recommendations. That £7,500 is a big, direct chunk off the upfront cost — the single strongest reason a heat pump is affordable at all for many households.

Solar gets no equivalent cash grant for most owner-occupiers. What it does get is 0% VAT on residential solar and battery storage, which runs to 31 March 2027 and then reverts to 5% — worth roughly £1,400 on a £7,000 install, but not permanent. On top of that, the SEG pays a small ongoing income for exported units. It’s help of a different kind: a tax saving and an income stream, rather than a lump-sum grant. (Heat pumps also qualify for that 0% VAT, on top of the grant.)

Neither form of help is a reason to rush a five-figure decision. A poorly-sized heat pump in a draughty house, or panels on a shaded north roof, still won’t stack up — grant or no grant.

Who each one suits

A heat pump is likely the stronger move if:

• Your gas boiler is old and near the end of its life, so you’re facing a replacement anyway.
• Your home is reasonably well insulated (or you’re willing to improve it) — heat pumps work best in homes that hold heat.
• Cutting your carbon footprint and coming off gas matters to you, not just the bill.
• You can access the £7,500 grant and are happy to move onto a heat-pump tariff to get the best running costs.

Solar is likely the stronger first move if:

• You use a decent chunk of electricity during daylight — someone home in the day, or you can shift the washing, dishwasher and hot-water heating into daylight hours.
• You have a reasonably sun-facing, unshaded roof.
• You want a clear, modellable bill saving with a payback you can check, rather than a mainly carbon-and-comfort case.
• Your boiler still has years left in it, so there’s no pressing reason to touch your heating yet.

If you’re weighing whether solar is right for your situation at all, the is solar worth it page runs through the honest yes-and-no, and when solar is not worth it covers the cases where we’d tell you to wait.

Why they work best together

Here’s the part that reframes the whole “versus” question: solar and a heat pump complement each other. A heat pump turns your heating into an electrical load — and solar generates electricity. Run them together and some of your winter-shoulder heating and summer hot water can come straight from your own roof rather than the grid.

The honest caveat is seasonal. A heat pump works hardest in deep winter, exactly when a UK solar array is generating least — only around a third of its annual output falls between September and February. So solar won’t power your heating through a cold January. What it does do well is cover heating and hot-water demand in spring, autumn and summer, and offset the heat pump’s shoulder-season running costs. Pair the two with a battery and a cheap-overnight tariff, and you can charge up when electricity is cheapest and lean on solar when the sun’s out — a blend that quietly improves both sets of numbers.

That’s why the sequencing usually matters more than the choice. Many homes fit solar first (clear payback, no dependence on the state of your boiler), then add a heat pump when the boiler finally gives up and the grant is in play — by which point the roof is already feeding the new electrical load.

How to decide for your home

Two quick questions get you most of the way:

1. Which bill is bigger — and more urgent? If your heating is expensive and your boiler is on its last legs, the heat pump (with its £7,500 grant) is probably the pressing decision. If your boiler is fine and you just want to cut your electricity bill, solar is the cleaner, faster-payback move.
2. What matters most — a modellable saving, or getting off gas? Solar gives you the first; a heat pump gives you the second, with running costs that are roughly a wash unless you’re on the right tariff.

For most owner-occupiers with a working boiler and a decent roof, the honest recommendation is: start with solar, because the savings case is clear and doesn’t hinge on your heating system, then look at a heat pump when your boiler needs replacing. See the real numbers behind that on the benefits of solar panels and cost pages, then put your own figures into the savings calculator. And whichever way you lean, let an MCS-certified installer’s survey confirm the detail for your specific home — because these are ranges, not promises, and the honest figure only comes from your own roof, your own boiler and your own usage.