How does a solar thermal (hot water)
system work?
- Solar Collector
- Cylinder with Solar Coil at the bottom and coil for boiler
at the top
- Boiler or other space heating source
- Hot water tap
- Cold water mains in
- Pump station used to circulate water from the collector to
the user application
- Controller uses temperature sensors to monitor heat
differences between the collector and the water in the tank
and switches the pump on and off accordingly
- Expansion vessel to contain increased water volume in the
system due to rise in temperature and hence increased
pressure, of water
The main components of a solar thermal system are the dual coil solar cylinder, pump station, and collector. Collectors are either flat plate or evacuated tube.
Solar radiation is absorbed by the collector, heating the water either directly (the water is pumped through a manifold connected to the collector) or indirectly (the domestic water is heated by a heat-transfer fluid).
The controller switches the pump on when the difference between the temperature on the roof and the temperature at the bottom of the cylinder is sufficiently large (typically 10 degrees). The pump circulates water or heat transfer fluid around the system and heat is transferred from the roof into the bottom of the tank.
Top up heat is provided by the boiler as required.
For more information on the individual components, click here.