RLB_UK_Riders_Digest_2013

How does it work?
In a typical system, a heat transfer medium (generally a
water/antifreeze mixture) travels through a series of heat
conducting tubes known as a heat collector. During its
circulation through the tubes, the fluid picks up heat which
is then transferred to the domestic hot water supply.
Commercially available systems are either indirect (closed
loop) or direct (open loop). With the more common indirect
system, circulating fluid flows through the collector and
transfers the heat to a hot water tank.
With direct systems, water is heated as it is passed directly
through the collector, and flows to the dwelling where it
can be used for bathing, washing etc. Direct systems can
have higher efficiencies than indirect systems, but will
have higher running costs, as the potential for scaling and
corrosion of the internal surfaces can lead to increased
servicing and maintenance.
A basic solar thermal collector comprises of a translucent
cover, an absorption plate, and the heat transfer system.
There are two main types of collector, known as flat plate
and evacuated tube. Flat plate consists of an insulated
metal box with a glass or plastic cover and a dark or black
coloured absorber plate. Evacuated tube collectors consist
of rows of parallel transparent glass tubes, each containing
an absorber tube covered with a selective coating.
The system produces no noise or harmful emissions
Minimal operational or maintenance costs
Does not require direct sunlight, but care must taken to
avoid overshadowing
Grants available from the Renewable Heat Initiative
Limitations
Planning issues could be a problem
May have implications for load capacity of roof or building
structure
May have implications for availability of plant space on roof
© Rider Levett Bucknall UK 2013 107