Solar Thermal Panels in the UK
Solar thermal panels (also called solar collectors) use sunlight to heat water directly. Unlike solar PV panels which generate electricity, solar thermal systems heat a fluid that transfers heat to your hot water cylinder.
A typical system provides 50–70% of a household's hot water needs annually. Solar thermal costs £3,000–£5,000 installed in the UK. MCS certification is required for quality-assured installations.
Last updated March 2026
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
Quick Answer
Solar thermal panels in the UK cost £3,000–£5,000 installed. They provide 50–70% of a household's annual hot water needs. There is currently no specific UK grant for solar thermal (the RHI has closed and BUS does not cover solar thermal). Most new installations now favour solar PV instead, which can heat water via a diverter and also generate electricity.
How do solar thermal panels work?
Solar thermal panels absorb sunlight and convert it to heat. A heat transfer fluid (usually a glycol/water mix) circulates through the panels and into a coil inside your hot water cylinder. A controller monitors temperatures and activates the circulation pump when the panels are hotter than the water in the cylinder.
How the system works
- Sunlight heats the solar collector panel on your roof
- Heat transfer fluid circulates through the panel, absorbing heat
- The hot fluid flows to a coil inside your hot water cylinder
- Heat transfers from the fluid to your stored water
- The cooled fluid returns to the panel to be reheated
- A controller manages the system automatically
Seasonal output in the UK
- Summer: ~95% of hot water needs
- Spring/Autumn: ~50% of hot water needs
- Winter: ~15–20% of hot water needs
- Annual average: 50–70% of hot water needs
Types of solar thermal panels
| Type | Efficiency | Cost (installed) | Best For |
|---|---|---|---|
| Flat plate collectors | 60–70% | £2,500–£4,000 | Most UK homes |
| Evacuated tube collectors | 70–85% | £3,000–£5,000 | Cloudy climates, limited roof space |
Flat Plate
Lower cost, robust construction, good in direct sunlight. 25+ year lifespan. Most popular choice in the UK. Flat glass panel, approximately 2m² per panel.
Evacuated Tube
Higher efficiency in overcast and cloudy conditions — performs better in the UK climate. Lighter weight but can be more fragile. Glass tubes arranged in rows.
Solar thermal vs solar PV — which is better?
| Feature | Solar Thermal | Solar PV |
|---|---|---|
| Purpose | Hot water only | Electricity (all uses) |
| Efficiency | 60–85% (heat capture) | 18–22% (electricity) |
| Installed cost | £3,000–£5,000 | £5,000–£10,000 |
| Grant available | No current grant | No direct grant (SEG for export) |
| Annual saving | £150–£350 | £400–£1,000 |
| Payback period | 10–15 years | 6–9 years |
| Export payments | No | Yes (Smart Export Guarantee) |
| Battery compatible | No | Yes |
| EPC improvement | Good | Very good |
| Maintenance | Annual service recommended | Minimal |
Our recommendation
For most UK homes in 2026, solar PV is the better investment. It's more versatile (powers everything, not just hot water), qualifies for Smart Export Guarantee payments, has a faster payback, and can pair with batteries and EV chargers. Solar thermal still makes sense for: homes with very high hot water demand (large families, B&Bs), properties where roof space is very limited, or existing installations needing replacement. See our solar panel costs guide.
Solar thermal costs in the UK
| Item | Cost Range |
|---|---|
| Solar thermal panels (2 panels) | £1,200–£2,000 |
| Hot water cylinder (twin coil, 200–300L) | £400–£800 |
| Installation and plumbing | £1,000–£1,800 |
| Scaffolding | £400–£600 |
| Total installed cost | £3,000–£5,000 |
Running costs are minimal — just the circulation pump (£10–£20/year electricity). Note: there is currently no UK government grant specifically for solar thermal. The Renewable Heat Incentive (RHI) has closed and the Boiler Upgrade Scheme (BUS) does not cover solar thermal systems.
UK solar thermal grants & incentives
There is currently no dedicated UK government grant for solar thermal panels. The Renewable Heat Incentive (RHI) closed to new applicants in March 2022, and the Boiler Upgrade Scheme (BUS) does not cover solar thermal systems.
What you should know
- MCS-certified installer is still recommended for quality assurance
- Solar thermal can improve your EPC rating, adding value to your home
- VAT on solar thermal installations is 0% (since April 2022)
- Some local councils offer green energy grants — check your local authority
- Solar thermal contributes to renewable heat targets under Building Regulations
Although no direct grant is available, the 0% VAT rate significantly reduces the installed cost. See our full solar grants guide for details on available UK incentives.
How much can solar thermal save?
Savings depend on your current hot water fuel source, household size, and water usage. Here's what a typical UK household can expect:
| Current Fuel | Annual Hot Water Cost | Solar Thermal Saving | Payback period |
|---|---|---|---|
| Electricity (immersion) | £500–£800 | £250–£500/yr | 8–14 years |
| Oil boiler | £350–£500 | £175–£300/yr | 12–18 years |
| Gas boiler | £300–£450 | £150–£275/yr | 13–20 years |
1,200–1,500
kWh saved per year
50–70%
of hot water needs
20+ years
system lifespan
When does solar thermal still make sense?
While solar PV is generally the better investment for most homes, there are situations where solar thermal is a strong choice:
High hot water demand
Large families (4+ people), B&Bs, guesthouses, or homes with multiple bathrooms. Solar thermal is more efficient per square metre specifically for water heating than PV + diverter.
Very limited roof space
If your roof can only fit 2–3 panels, solar thermal delivers more hot water per panel than the equivalent PV area would via a diverter.
Replacing an existing system
If you already have solar thermal and the panels need replacing, it's often cheaper to replace like-for-like than to switch to PV (new cylinder, wiring, etc.).
Combined with solar PV
Some larger homes install both — PV for electricity and thermal for hot water — using separate roof areas. This maximises total energy generation from available roof space.
Solar thermal installation
Installation typically takes 1–2 days. The most disruptive element is replacing the hot water cylinder, which is required if your existing cylinder doesn't have a twin-coil setup.
Installation steps
- Home survey — system sizing and roof assessment
- Roof assessment — south-facing preferred, 30–60° pitch ideal
- Hot water cylinder replacement — must be twin-coil solar cylinder (200–300L)
- Panel mounting — 2–4 panels, ~4–6m² on roof
- Plumbing connection — insulated pipes between panels and cylinder
- Controller installation — differential temperature controller and pump
- Commissioning — fill with glycol, pressurise, and test
- Post-installation EPC — recommended to document energy improvement
Maintenance requirements
- Annual visual inspection of panels and connections
- Glycol fluid check and top-up every 3–5 years
- Full glycol replacement every 5–7 years (£80–£170)
- Pump replacement after 10–15 years (£120–£250)
- No cleaning required in most cases (rain handles it)
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Get a Quote ↓Solar Thermal FAQ
How much hot water can solar thermal panels provide in the UK?
A typical system provides 50–70% of annual hot water needs. In summer, solar thermal can provide almost all your hot water. In winter, you'll still need a boiler or immersion to top up.
Do solar thermal panels work in winter in the UK?
Yes, but at reduced output. Expect ~15–20% of your hot water from solar in winter months. The system still contributes on overcast days, just less than in summer.
Can I add solar thermal to my existing boiler?
Yes, but you'll need a twin-coil solar hot water cylinder. One coil connects to the solar panels, the other to your boiler. Your boiler acts as backup when solar isn't sufficient.
How long do solar thermal panels last?
20–25 years for flat plate collectors, 15–20 years for evacuated tubes. The glycol fluid should be checked and replaced every 5–7 years. Pumps may need replacement after 10–15 years.
Should I get solar thermal or solar PV?
For most homes, solar PV is a better investment in 2026. PV is more versatile, has faster payback, and qualifies for Smart Export Guarantee payments. Solar thermal is best for high hot water demand or very limited roof space.
Do solar thermal panels need planning permission in the UK?
No. Residential solar thermal installations are generally permitted development in the UK, under the same rules as solar PV panels. The panels must not protrude more than 200mm from the roof surface. Listed buildings and conservation areas may require planning permission.
Can I have both solar thermal and solar PV?
Yes, but it's rarely recommended for residential homes. A solar PV system with a diverter (like a Myenergi Eddi) can heat water with surplus electricity, effectively combining both functions. This is usually more cost-effective than installing separate thermal and PV panels.
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Related Guides
Sources
- MCS: Certified Installers & Products
- Energy Saving Trust: Solar Water Heating
- UK Government: Boiler Upgrade Scheme (BUS)
Last updated: March 2026
John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He fact-checks all content against official MCS and Ofgem data and maintains relationships with MCS-certified installers across the UK.
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