What is solar thermal transfer?
Solar technology can be divided into two areas: solar thermal transfer and photovoltaics.
Solar thermal transfer involves the use of collectors to convert sunlight into heat for hot
water supplies or auxiliary space heating. It is a specialist term for heat (it also covers
cooling) produced using solar energy.
What does a solar thermal system consist of?
Solar thermal transfer systems are made of at least one collector, heat storage unit,
solar circuit, and control unit with pump.
Diagram of a typical system
What types of collector are there?
The most common is the flat plate collector. It consists of a metal absorber in a sealed
housing, insulated on the back. The side facing the sun has a transparent glass cover. There
are also vacuum tube collectors, they are slightly more efficient but also more expensive.
Their absorber consists of a flat or curved strip of metal fitted in an evacuated glass tube. A
vacuum tube collector is made of a number of tubes whose ends are connected to a common
header.
 |
 |
| Flat Plate Collectors |
Evacuated Tube Collectors |
When is a house suitable for a solar thermal transfer system?
Solar radiation is sufficiently intense in the U.K. to operate a solar thermal transfer system
effectively. Ideally you require a roof surface that faces south, is free from shading and has a
pitch between 20° to 60°. Usually 3 to 5m2 of collector area is required for supplying hot
water. The storage tank requires an approximate footprint of 1m2 although larger tanks mean
more stored hot water especially through the summer.
It is possible to get the same energy yield from west or east orientated collectors with a
slightly larger surface area. Flat roofs and facades are also suitable for mounting collectors.
What proportion of my hot water requirements can I cover with a solar thermal transfer system?
A solar thermal transfer system for hot water supply in an average semi-detached or
detached house is designed to cover up to 100% of the energy demand during the summer
months of May to September. At our latitudes, a well-designed system can cover 60% of the
hot water requirements over the year.
How much energy can really be saved?
On average, a solar system (5m2 flat plate collector, 300 litre storage tank) saves
approximately 2300kwh per year compared with a conventional heating system, although the
amount saved will vary with the usage, weather conditions etc.
How can a solar thermal transfer system be installed on a building?
The following installation options are available:
- Integrated roof
- Roof mounted
- Flat roof
- Complete roof
- Canopy
- Façade
Most installations will not require planning permission and are covered by the General
Permitted Development Order as long as the property is not listed or in a conservation area
and the collectors do not protrude more than 200mm from the roof line.
How long will a solar thermal transfer system last?
Solar thermal transfer systems have a life in excess of 20 years.
Are there any grants available?
 Yes, there are grants available under the Low Carbon Buildings scheme.
Please see www.lowcarbonbuildings.org.uk for details. Installers have to
be approved under the Microgeneration Certification Scheme. Please look for the logo.
|
Download PDF