The Short Answer
On our estimates, a solar thermal (solar water heating) system costs about £3,500 to £7,000 installed, with no VAT until 31 March 2027. The Energy Saving Trust says it provides about 90% of your hot water in summer and 25% in winter, roughly half over a year.
It heats water, not your home, and it needs a hot water cylinder. With a combi boiler it usually means a new cylinder and a different boiler too, which is where the cost climbs.
Solar thermal prices
| Job | Typical cost |
|---|---|
| Solar water heating system, installed | £3,500 to £7,000 |
| A new unvented cylinder, if yours won't work with it | £1,100 to £2,650 |
How it works, and what you get
Panels on the roof heat a liquid that's pumped through a coil in your hot water cylinder or a thermal store. The Energy Saving Trust puts a typical installation at around £5,300, varying with the type of collector (evacuated tubes or flat plates) and the size. In summer it can cover about 90% of your hot water, in winter about 25%, so the boiler or an immersion heater tops it up.
Will it work with your boiler?
The Energy Saving Trust's guidance:
- You need a hot water cylinder, ideally indoors, though a garage can work. Most systems use one cylinder with an immersion heater or boiler coil near the top; some use two.
- A conventional boiler with a cylinder is often compatible, but the cylinder usually has to be replaced with a solar one.
- With a combi, you'd likely need a solar cylinder and to swap the combi for a conventional boiler or a heat pump: few combis are compatible.
So I'd only look at solar thermal if you already have a cylinder, ideally when it's due for replacement anyway. With a combi, I'd look at solar panels for electricity instead (about £6,500 to £9,000 for a typical system): see solar panel costs.
VAT and grants
HMRC zero-rates the installation of solar collectors, including the pipework, pump, storage cylinder, controls and heat exchanger, until 31 March 2027; then 5% from 1 April 2027. The Boiler Upgrade Scheme doesn't cover solar thermal: it's for heat pumps and biomass boilers.
If a quote for an installation in your home adds VAT at the standard 20% rate, query it.
Planning
The Energy Saving Trust says most systems are permitted development, with exceptions for listed buildings, conservation areas and national parks, so check with your council if any of those apply. The rules for panels on a house are on our solar panels page.
Get solar thermal quotes
Solar thermal is priced by the panels and the cylinder it heats.
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Frequently asked questions
How much does solar thermal cost?
On our estimates, about £3,500 to £7,000 installed, with no VAT until 31 March 2027.
Is solar thermal worth it in the UK?
It can be if you already have a hot water cylinder: the Energy Saving Trust says it gives about 90% of your hot water in summer and roughly half over a year. With a combi boiler, the extra cylinder and boiler change make it hard to justify.
Does solar thermal work with a combi boiler?
Rarely. The Energy Saving Trust says few combis are compatible, so you'd likely need a solar cylinder and a conventional boiler or heat pump instead.
Is there VAT on solar thermal?
No, until 31 March 2027: installing solar collectors in a home is zero-rated. From 1 April 2027 it's 5%.
Can I get a grant for solar thermal?
Not through the Boiler Upgrade Scheme, which covers heat pumps and biomass boilers.
How we priced thisView sources (4, 2 official)
Rules come from the legislation and official guidance, read at source. Prices are our estimates: we check them against trade price data, retailer shelf prices and specialists' price lists, then build them up from their parts so the totals add up. Below are the sources behind the page; the trade price guides we only compare against aren’t listed. Where sources disagreed, we've said so. More on our method.
- IndustrySolar water heating (20 May 2026), Energy Saving Trust. Checked 16 Oct 2026.
- OfficialEnergy-saving materials and heating equipment (VAT Notice 708/6), HM Revenue & Customs. Checked 16 Oct 2026.
- OfficialApply for the Boiler Upgrade Scheme: what you can get, GOV.UK. Checked 15 Oct 2026.
- IndustrySolar panels, Energy Saving Trust. Checked 16 Oct 2026.
