The fluid filled pipe from the solar panel enters the water tank and coils round many times. The heat from the pipes is transferred to the water in the tank. A small device in the tank stirs the water to help with the transfer of the heat from the fluid pipes.

One common use of solar power is to heat domestic water. Although a typical system is expensive to buy, it pays for itself over a period of five to ten years. Also owning and using a system such as this shows that the owner is serious about saving energy and protecting the environment.
A typical solar water heating system is seen in the diagram below. The suns rays pass through the glass panel, warming the fluid pipes inside the unit. The pipes are painted black to ensure that they absorb as much heat as possible. The reflective silver surface behinds the pipes reflects heat back onto the pipes, further raising the fluids temperature.
The fluid pipes running through the solar panel are sealed and the fluid is pumped round the sealed system. The pipes run through the domestic water tank and the heat they carry is transferred to the water in the tank. The coil of pipes is called a ‘heat exchanger’.

Often solar panels (sometimes called collectors) are placed on the roof of a building where the sun’s rays are not blocked out by trees or other obstructions. Solar panels are quite expensive to manufacture and at the moment they are not widely used in countries such as the UK. Why do you think this is so?