Solar thermal panels use free energy from the sun to heat your hot water, and in 2026 they benefit from 0 per cent VAT until 31 March 2027. This guide covers how they work, what they cost, how much you can save, why they do not qualify for the Boiler Upgrade Scheme, and how they compare with solar panels.
Solar thermal panels use free energy from the sun to heat your hot water. They are one of the oldest and simplest renewable technologies for UK homes, and in 2026 they are having a quiet revival as households look for lower cost ways to cut the energy used on hot water. This guide explains how solar thermal works, what it costs in 2026, how much you can realistically save, whether it qualifies for any funding, and the checks to make before you commit.
What solar thermal panels are
Solar thermal panels, also called solar water heating collectors, sit on your roof and capture heat from daylight. That heat is transferred through a fluid to a coil inside a hot water cylinder, warming the water stored there. Unlikesolar panelsthat generate electricity, solar thermal produces no power at all. It does one job, and it does it well, which is heating water.
There are two main collector types. Flat plate collectors are a sealed panel with a dark absorber plate behind glass. Evacuated tube collectors use a row of glass tubes, each holding an absorber in a vacuum that reduces heat loss. Evacuated tubes tend to be a little more efficient in cold and dull conditions, while flat plate panels are usually cheaper and more robust. Both work well on a typical UK roof.
How a solar thermal system works
The system is straightforward. A pump moves a water and antifreeze mixture through the roof collector, where it warms up. It then passes through a coil in a twin coil hot water cylinder, giving up its heat to the stored water, before returning to the roof to warm again. A controller runs the pump only when the roof collector is hotter than the water in the cylinder, so the system does not work against itself.
Solar thermal almost always works alongside your existing heating. Your gas boiler, heat pump or immersion heater tops the cylinder up when the sun cannot do the whole job, which in the UK is most of the winter. In summer, a well sized system can provide almost all of your hot water for weeks at a time.
One point worth understanding is that solar thermal pairs naturally with a heat pump. Anair source heat pumpheats a cylinder too, and on bright days the solar collector can lift the water temperature and reduce how hard the heat pump has to work. That said, most heat pump owners now favour solar PV with a diverter for the same effect, because the electricity is more flexible. The right combination depends on your roof space, your budget and how much hot water your household gets through.
How much hot water it can provide
According to the Energy Saving Trust, hot water accounts for around 11 per cent of a typical household energy bill. A properly sized solar thermal system can provide roughly 50 to 70 per cent of a home's annual hot water demand. The figure is high in summer, often close to 100 per cent, and low in winter when daylight is short and weak.
You will need around five square metres of roof that gets direct sunlight for the main part of the day, ideally facing somewhere between south east and south west. A shaded or north facing roof is not suitable. Because output varies so much across the year, solar thermal is designed to reduce the work your main heating system does rather than replace it.
What solar thermal panels cost in 2026
For a typical three bedroom UK home, a complete solar thermal system in 2026 usually costs between £4,000 and £6,000 fully installed, including the collector, pump, controller and a new twin coil hot water cylinder. Simpler installations on an easy roof can come in lower, while larger evacuated tube systems or homes that need a new cylinder and extra pipework can sit at the higher end or slightly above.
The single biggest variable is the cylinder. If your home already has a suitable twin coil cylinder the cost falls, but most installations include a new one because the second coil is what allows the solar input to work alongside your boiler or immersion heater.
The 0 per cent VAT saving in 2026
There is one clear piece of financial support worth knowing about. Solar thermal collectors are on the government list of qualifying energy saving materials, which means their installation currently benefits from 0 per cent VAT in Great Britain. This zero rate applies until 31 March 2027, after which the rate is due to return to the reduced level of 5 per cent. On a system costing several thousand, paying no VAT rather than 5 per cent or 20 per cent is a meaningful reduction, so 2026 is a good year to install if you are already considering it.
Does solar thermal qualify for the Boiler Upgrade Scheme
This is the most common question, and the answer is no. The Boiler Upgrade Scheme, or BUS, only paysgrantsforair source heat pumps, ground source heat pumps, water source heat pumps, air to air heat pumps in certain cases and biomass boilers. Solar water heating is not on the list of eligible technologies, so you cannot claim a BUS grant towards it.
That does not mean solar thermal has no place in a funded upgrade. Many households combine a grant funded heat pump under BUS with other measures over time. If you are weighing up low carbon heating more broadly, our guide to theWarm Homes Plansets out how the wider funding picture is changing, and it is worth understanding whichgrantsapply to which technology before you spend.
How much you can save
Savings depend heavily on what your solar thermal system is offsetting. If it is reducing the amount of electricity an immersion heater uses, the saving per unit is high because electricity is expensive, and annual savings can reach the higher end of roughly £100 to £230 a year. If it is offsetting mains gas, which is cheaper per unit, the annual saving is more modest.
Solar thermal is best understood as a long term, steady saving rather than a fast payback. The panels have few moving parts and typically last 20 years or more, so the value builds up over time. Homes that use a lot of hot water, such as larger families, tend to see the strongest case because there is more demand for the free heat to displace.
Solar thermal compared with solar PV
It is easy to confuse solar thermal withsolar panelsthat generate electricity, but they are different technologies for different jobs. Solar photovoltaic, or PV, produces electricity you can use anywhere in the home or export to the grid. Solar thermal produces heat that goes straight into your hot water.
For many households in 2026, solar PV is the more flexible choice because the electricity can run appliances, charge a battery or feed a heat pump, and it can earn money through an export tariff. Solar thermal is more specialised and can be very efficient at its one task, but it only helps with hot water. If roof space is limited, most people now lean towardssolar panelsfor that flexibility, sometimes pairing PV with a hot water diverter to heat the cylinder using spare electricity. Oursolar panelsguide explains the PV route in more detail if you want to compare the two.
Is solar thermal right for your home
Solar thermal tends to make the most sense when several things line up. You have an unshaded roof of the right orientation with about five square metres of space. Your household uses a decent amount of hot water. You already have or are happy to fit a hot water cylinder, which rules out most homes that rely purely on a combi boiler with no cylinder. And you value a simple, durable system that quietly cuts your hot water energy for decades.
If your roof space is limited and you can only fit one technology, solar PV is usually the stronger all round investment. If you have plenty of roof and specifically want to cut the energy used on hot water, solar thermal is a sound and proven option.
Choosing an installer
For any solar water heating installation, use an installer certified under the Microgeneration Certification Scheme, known as MCS. MCS certification covers solar thermal as well as heat pumps and solar PV, and it is the recognised mark that the product and the installation meet a defined standard. Using an MCS certified installer also protects you if you later want to sell the home or demonstrate the quality of the work.
Before signing anything, follow a few simple checks.
- Confirm the installer is MCS certified for solar thermal specifically, not only for other technologies.
- Ask for a written estimate of annual solar contribution based on your roof, not a generic figure.
- Check whether a new twin coil cylinder is included in the price, as this is a common hidden extra.
- Ask how the system integrates with your existing boiler or immersion heater controls.
- Get at least two quotes so you can compare the collector type, cylinder and workmanship.
Planning permission and roof suitability
For most homes, fitting solar thermal panels is treated as permitted development, meaning you will not need planning permission. There are limits to be aware of. The panels should not project too far above the roof surface, and they should not be installed on a wall or roof slope that faces a highway if your home is in a conservation area or a designated setting. If you live in a listed building, permission is almost always required, so check with your local planning authority before you proceed.
Roof condition matters too. Because the collectors are designed to last two decades or more, it is sensible to fit them to a roof that is in good repair. If your roof is likely to need re covering within a few years, it is usually better to do that work first, so the panels do not have to be removed and refitted.
Flat roofs and ground mounting
Solar thermal is not limited to pitched roofs. Collectors can be mounted on a frame on a flat roof, angled to catch the sun, or in some cases fitted at ground level if there is a suitable unshaded spot. These options can add to the cost because of the mounting frame and extra pipework, but they open up solar thermal to homes where the main roof is unsuitable.
Maintenance and running costs
Solar thermal systems are low maintenance. The main ongoing tasks are keeping an eye on the pump and controller, and periodically checking the antifreeze fluid, which is usually replaced every few years as part of a service. The pump uses a small amount of electricity, but this is minor compared with the heat the system delivers. A professionally installed system should run for many years with only occasional attention.
The bottom line for 2026
Solar thermal is not the flashiest renewable technology, and it will not power your home or earn export income the waysolar panelscan. What it does is cut the energy your household spends on hot water, reliably and for a long time. In 2026 the 0 per cent VAT relief until March 2027 makes it a slightly cheaper year to install, even though there is no dedicated grant.
Forhomeownersweighing up their options, the sensible approach is to look at the whole picture. Compare solar thermal against solar PV with a diverter, think about your hot water demand, and factor in any wider heatinggrantsyou might qualify for.Landlordsin particular should consider how any measure fits alongside insulation and heating upgrades that carry funding. If you would like tailored advice, our team can talk through thegrantsand measures that suit your property.
