Solar thermal: heating your hot water from the roof

Flat plate collectors look like a slim glazed panel and sit neatly on a roof. Evacuated tube collectors use rows of glass tubes with a vacuum that reduces heat loss, so they collect more heat per square metre in cooler weather but are more visible on a roof. Both work in the UK; the choice depends on roof space, orientation and looks.

MCS notes that the fluid in the circuit is a mix that prevents freezing, and that performance depends on which way the roof faces, shading and your local weather. A south-facing roof with little shade is ideal; east or west can work with a larger collector area.

Solar thermal heats stored water, so it needs a hot water cylinder, usually a twin-coil cylinder with one coil for the solar circuit and one for the boiler or heat pump. Homes with a combi boiler and no cylinder would need one adding, which changes the project considerably.

It pairs well with a system or regular boiler, a biomass boiler and some heat pump set-ups. Where a heat pump already heats the cylinder efficiently, the extra saving from solar thermal is smaller, and some households choose solar PV with a diverter instead. Solar hot water systems can reach high temperatures and pressures, so Approved Document G expects all components to be rated for them, and an unvented cylinder is notifiable work that needs a suitably qualified installer.

Solar equipment on a house is often permitted development in England, but there are limits. On a pitched roof, panels must not sit above the highest part of the roof, excluding the chimney, and must not project more than 200mm from the roof slope. Listed buildings and scheduled monuments are excluded, and in a conservation area or World Heritage Site panels must not go on a wall facing a highway. The rules were updated on 27 August 2026 with a transitional period to 27 August 2027, so ask the installer which version they are relying on.

Building Regulations normally apply to roof-mounted solar: the roof has to be shown to carry the extra weight, and some strengthening may be needed. The pipework runs from roof to cylinder, so the route through the loft and the insulation of those pipes should be in the quote.

Source: legislation.gov.uk · planningportal.co.uk

Solar collectors with their pipework, pump, controls, heat exchanger and storage cylinder count as solar panels in HMRC's VAT notice, so installing them in a home is zero-rated until 31 March 2027. There is no Boiler Upgrade Scheme grant for solar thermal.

In Scotland, the Home Energy Scotland scheme offers an interest-free loan towards solar thermal, but no grant. MCS publishes average installation costs from its data dashboard, shown below.

• collector type, size and number, and the roof they go on
• cylinder: new twin-coil or existing, and its size
• pump station, controller and expansion vessel
• pipe route and insulation from roof to cylinder
• structural check and any planning or listed building consent
• MCS certificate and handover pack with the servicing schedule

Source: gov.uk

Tell us your roof type and direction, the current boiler and whether you have a hot water cylinder. Solar heating installers in your area see the request with your personal details removed. Exactly one can buy it, and then it is taken off our platform. The installer pays Offrano; you do not.

Before the installer gets your details we email you its name, address and phone number. We cannot guarantee that anyone takes the request, and you do not have to accept any quote. Offrano only checks that the buyer is a registered business, so confirm the installer's MCS certification yourself.