Solar water

Solar water
Solar water heating is a well known renewable energy technology in the UK. It can be used to provide hot water at temperatures of between 55 and 65ºC.

Solar thermal or solar hot water systems work by absorbing energy from the sun and transferring it, using heat exchangers, to heat water. Types of solar water heating system

There are three main types of solar heating collector that are suitable for mounting on buildings. These are:

Flat-plate collectors — a sheet of black metal that absorbs the sun’s energy encases the collector system. Water is fed through the system in pipes which conduct the heat to the water.

Evacuated tubes — a series of parallel glass heat tubes grouped together. Each tube contains an absorber tube. Sunlight passing through the outer glass tube heats the absorber tube contained within it, and in doing so, the heat is transferred to water flowing through the tube.

Solar matting — a range of extruded hollow sections of flexible black material that can be used for solar collection. Water passes through the hollow tubes, absorbing the heat from the sun.

Site suitability
Ideally, systems should be roof-mounted and oriented to face between south-east and south-west. It is also advantageous to be able to locate equipment (such as the heat exchangers) in the roof space close to the collectors.

A system for a small office would use around 4m2 of roof space, so this must be taken into account in the design of a building. Retrofitting is a more costly option due to the complex nature of installation. However, a solar thermal system could be integrated into an existing gas-boiler system.

Planning permission is not usually required for small-scale solar water heating systems. Businesses should contact a planner at their local council for advice before proceeding.