Solar Thermal

There are two key types of solar thermal energy collectors: flat plate and evacuated tubes. Evacuated tubes are the more efficient, but also more costly technology. Systems may be either ‘drain-back' or sealed/ pressurized. The latter are more common in the UK and require anti-freeze in the heat-exchange fluid, making heat exchange less efficient (see links below for further information). Systems can be mounted on the façade, the roof, or at floor level. They are normally supplied in fixed panel sizes and feed into a twin coil thermal store.

Typically, a solar hot water system feeds the hot water system only. Around 50 per cent of hot water requirements can usually be covered. For a standard three bedroom house a four m² panel is typical.

In larger commercial premises solar collectors can be used to pre-heat space heating or even industrial water which is then boosted by conventional boilers. This application can be used for residential buildings as well, but the load-matching between the solar output and the space heating demand is poor. There are numerous precedents on the continent for the use of solar systems for space heating as well, however these systems are very expensive since both the storage tank and the collectors need to be significantly oversized in this case.