Small scale solar thermal energy

Small scale solar thermal energy

A solar collector uses the sun’s radiant energy to heat water. Heated water is pumped via an insulated pipe to the thermal store where the heat is transferred through the pipe wall. The collector is normally fixed on the roof of a building, but installations can also be located away from buildings.

Solar hot water diagram

Q. Are all houses suitable for solar panels?

A. To generate a significant annual yield of energy you will need an area of 2 to 4m2 of south-east to south-west-facing roof that receives  direct sunlight during the main part of the day. It must not be obstructed by trees or other structures, including chimneys or dormer windows that would cast shadows on the collector.

Collectors can still be effective on east and west faces, but the annual yield will be lower.

Consent for an installation on some houses may be a problem.
see ‘What approvals do I need?’

Q. Is it difficult to install solar collectors onto an older roof?

A. The weight of the collector and its fixing frame  will be borne by the roof rafters. These must be capable of supporting the combined weight of the collector (with water in it) and its supporting framework. The supplier or installer will be able to supply this information. 

Tiles or slates will inevitably be broken during installation, however careful the installer. It is therefore advisable to have replacements readily to hand. It is also important to remember that replacements for stone or old handmade tiles can be expensive and difficult to find. 

Q. Do solar collectors need to be fitted to the roof?

A. If fixing collectors to the roof is either unacceptable or impracticable it is sometimes possible to position them elsewhere – on an outbuilding for example – with the pipes buried and routed back to the storage tank. If space allows, the collector may also be mounted on the ground.

Q. How much energy can a typical domestic roof- top solar collector make?

A. Most domestic systems are capable of providing all the hot water requirements of a typical home during the summer months (when more solar energy is available), or about 50 per cent of the annual requirement..

Q. What grants are available for micro-generation technologies for householders?

A. The Department of Energy and Climate Change ( DECC) run a Low Carbon Buildings Programme that provides micro- generation grants for householders

Q. How can I find an Installer?

A. Recipients of Low Carbon Buildings Programme grants must use accredited installers and materials. The list of accredited installers is a useful resource even if you are not applying for a grant for all types of renewable technologies.

Q. How much does a domestic system cost?

A. A typical domestic solar thermal installation costs £3,500 – 4,500. (2007 prices)

Q. Do changes need to be made to the existing boiler or hot water storage tank?

A. No changes are required to the existing boiler,  which will still feed into the hot water tank. The property’s existing hot water storage tank will normally need to be replaced with a larger tank for the solar power to feed into. The installer can advise on the appropriate tank size depending on the number of occupants and how the hot -water is to be used. A typical domestic hot-water tank has a capacity of 120 litres and is about 0.5 metres in diameter and 1 metre tall. A tank for the solar collector will have a capacity of 200 to 300 litres and be of a similar diameter, but 1.5 metres to more than 2 metres in height.

Q. Is planning permission needed to install a solar collector on a house?

See What approvals do I need?


Small scale thermal energy

Small scale thermal energy

This guidance looks at what a homeowner would need to consider when installing a system on a traditionally constructed building.


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