A solar thermal installer is an MCS certified specialist who installs solar thermal collector systems - either flat plate panels or evacuated tube collectors - on rooftops to heat domestic hot water. Unlike solar PV which generates electricity, solar thermal directly heats a glycol fluid circulated through roof-mounted collectors and transfers that heat to a hot water cylinder via a heat exchanger coil. A well-sized system can provide 50-70% of a household's annual hot water demand, with the greatest contribution in spring and summer.
What they do
- Roof survey and orientation and shading assessment
- Solar thermal system design (flat plate or evacuated tube)
- Cylinder and system specification including twin-coil cylinder
- Collector and pipework installation and commissioning
- MCS certificate issue on completion
- Integration with existing boiler or heat pump backup
- Swimming pool heating system design and installation
- Annual servicing and antifreeze glycol check
When you need one
A solar thermal installer is needed when you want to reduce hot water heating costs using renewable solar energy.
Typical costs (UK, 2025)
| Job type | Typical cost |
|---|---|
| Solar thermal flat plate system (supply and install) | £3,000 - £5,000 |
| Evacuated tube system (supply and install) | £3,500 - £6,000 |
| Pool heating system (supply and install) | £2,000 - £5,000 |
| Cylinder replacement if required | £500 - £1,200 |
| Annual service | £100 - £180 |
Costs vary by roof access, system size and whether a new cylinder is required. Always obtain at least two MCS certified quotes.
Qualifications to look for
MCS certification is the quality standard for solar thermal installers. Required for grant-funded installations. Verify at mcscertified.com before appointing.
The BPEC solar thermal qualification covers system design, collector installation, cylinder specification and commissioning. It is the primary trade qualification alongside MCS certification.
How to find a reputable solar thermal installer
Frequently asked questions
Is solar thermal better than solar PV for hot water?
Solar thermal is more efficient at converting solar energy to heat but less flexible - it only heats water. Solar PV generates electricity that can heat water plus run appliances, making solar PV plus immersion heater or heat pump an increasingly preferred combination.
Does solar thermal work in winter?
It generates useful heat on sunny winter days but output is significantly lower. A well-designed system covers 50-70% of annual hot water demand averaging across all seasons.
What type of cylinder do I need for solar thermal?
A twin-coil hot water cylinder is required - one coil for the solar thermal circuit and one for the boiler or heat pump backup.