All you need to know about solar heating...
What is it?
A solar water heater is a series of tubes (usually 2.5 square metres), mounted on south-facing roofs, that use the heat of the sun to warm a mix of water and anti-freeze. This is then pumped into a large hot water tank, thereby heating it up. When the water mix has transferred its heat it is pumped back to the roof to be heated again.