Solar Thermal Panels - How They Work
Solar power, energy from the sun, is free and inexhaustible. By the time it reaches the earth's surface, the energy in sunlight has fallen to about 1,000 watts per square meter. If you average this over the entire surface of the earth each square meter collects the energy equivalent of a barrel of oil. So each day, on average, a square meter collects 4.2 kilowatt-hours of energy.
In a solar thermal collector (or panel), light energy from the Sun is converted into heat energy. This heat energy is transferred to a heat transfer medium that is circulated through the collector by means of a small pump. The heat transfer liquid is pumped to a dual coil solar hot water cylinder, where it flows through one of two heat exchange coils. Heat is transferred from the coil to the surrounding water within the cylinder. This water is then available as hot water from the hot water taps. The second coil is connected to the boiler in the same way as a conventional cylinder is connected.
Collectors come in two main types: flatplate and evacuated tube. Evacuated tube collectors are generally considered to be more efficient than flatplate collectors. The choice of collector is largely a matter of personal preference. However, the choice may be restricted if the available roof area is small.
Most solar thermal control systems (the circulation pump and the solar controller) are powered using mains electricity.