✔ Solar thermal panels use the sun’s energy to provide hot water for your home
✔ They won’t provide all your hot water but they will make a modest dent in your bills
✔ Fill out the form above to get solar panel quotes from trusted local installers
The Smart Export Guarantee (SEG) launched on 1st January 2020 to replace the old Feed-in Tariff. Check out our guide to the SEG here to find out how much you could earn.
What’s In This Guide to Solar Thermal Panels?
What Are Solar Thermal Panels?
A solar thermal system uses warmth from the sun to heat water for your home or business.
Solar thermal panels are usually made of tubes, called collectors, that are filled with liquid which is warmed by the sun’s heat. The warm fluid is then pumped through a coil in your water cylinder, warming your water up.
A boiler or electric immersion heater can be used to top up the temperature of the water if it isn’t high enough, or to provide hot water at night. Solar water heating cannot provide all your hot water; the Energy Saving Trust estimates that it will provide about 60% of it. But that still reduces your fossil fuel consumption and hot water bills by more than half.
On top of the savings you make, the government also pays you for the energy you generate through a scheme called the Renewable Heat Incentive.
Types of Solar Thermal Panel
There are 2 main types of solar thermal panel: flat plate collectors and evacuated tube collectors. The difference is in the way they are designed:
Flat plate collectors have a plate inside an insulated box which absorbs the sun’s heat. The fluid is pumped through tubes inside the plate, which warms it up.
Evacuated tube collectors have 2 sets of tubes instead: outer tubes made of glass, and inner tubes made of either metal or glass which the liquid is pumped through. The outer and inner tubes are separated by a vacuum.
Evacuated tube collectors are usually more efficient, because a vacuum is an excellent insulator. So an evacuated tube collector will provide more heat than a flat plate collector of the same size. For this reason, flat plate collectors tend to be cheaper and some people also prefer the way they look, as they can sometimes be integrated into the roof.
Benefits of Solar Thermal Panels
✔ Free hot water. Sunlight costs nothing, so once you’ve paid for and installed the panels, all the energy you get from them is free.
✔ Solar energy can never run out. The system will work best in bright sunlight, but it will generate some power whenever there is daylight, all year round. And you still have a source of hot water if your gas or electricity goes off.
✔ They’re environmentally friendly. Using solar hot water does not produce pollution or add to global warming.
✔ Low maintenance. Solar panels need little maintenance. The Energy Saving Trust recommends having your system checked over by an accredited installer every 3 to 7 years – your installer should give you guidance on this. Most solar thermal systems have a 5 to 10-year warranty.
Disadvantages of Solar Thermal Panels
✘ Their efficiency will vary. The panels will produce less energy on a cloudy day, and none at night; you will still be partly reliant on fossil fuels. If your roof doesn’t get a lot of sun, solar thermal panels won’t be suitable for you, because the expense will not be worth the return.
✘ You need a suitable hot water cylinder. You’ll usually need a special solar cylinder with 2 coils, either as a replacement for or in addition to the one you have right now. If you don’t have a hot water cylinder, you’ll have to think about whether you have space for one.
✘ They’re not easily compatible with combi boilers. It can be done, but since the main advantage of a combi boiler is that it only heats the water you need when you need it, and saves space by not having a hot water cylinder, adding a cylinder to store water contradicts the advantages of a combi.
How Much Do Solar Thermal Panels Cost?
You can expect to pay anywhere between £3,000 and £6,000 for solar thermal panels, including parts and installation. The Energy Saving Trust estimates between £4,000 and £5,000 for an average sized system.
The cost of the system will depend largely on its size. As a rough guide, you are likely to need at least 1 square metre of panels for each person in the house.
You can save money by installing the panels yourself, but since you are only eligible for the Renewable Heat Incentive (see below) if you use an accredited installer, this loss will probably undo any savings you make on installation costs.
How Much Money Will I Save With Solar Thermal Panels?
DISCLAIMER: Our partners no longer take appointments for homeowners looking to benefit from the Feed-in Tariff, which concluded on 31st March 2019
The financial benefits of solar thermal panels are twofold. You will save money on your energy bills because the sun will be heating your water for free, and you will be paid by the government for the energy you generate.
1) Savings on your energy bills
How much you save will depend on how much heat you get from your solar thermal panels, but it is likely to be a pretty modest amount.
The Energy Saving Trust estimates that solar thermal panels will save you £50 a year if you have a gas boiler, £55 if you have an oil boiler, £65 if you use coal, £80 if you have an electric boiler and £95 if you use LPG (liquid petroleum gas).
2) The Renewable Heat Incentive
This government scheme pays you for the renewable energy you produce for 7 years. You receive payments every quarter.
The tariff changes every 3 months. For April to June 2018 it is 20.66p/kWh of energy (up from 20.06p the previous quarter). Your payments will normally stay the same throughout the 7 years.
Based on figures from the Energy Saving Trust, here are our estimates for how much you can expect to earn from the Renewable Heat Incentive at the current tariff:
Using these figures, a 4-person household would recoup £405 x 7 = £2,835 in the 7 years of receiving the Renewable Heat Incentive. However, after the 7 years is up, the only financial gain will be the money you save on your energy bills.
Number of People in Household
System Size (metre sq.)
Total Savings with Gas Boiler
Total Annual Gain