The Sun is powered by a process known as nuclear fusion. At very high temperatures, hydrogen isotopes deuterium and tritium fuse together to form helium atoms. This forms large amounts of energy along with the emission of neutrons. The Sun emits electromagnetic waves which travel towards the earth at the speed of light, that's around 300,000km per second and taking just eight minutes to reach us. It is estimated that the amount of energy from the sun reaching Earth every minute is more than
the total energy used by the world in terms of fossil fuel use every year.
Different forms of solar power
Solar Thermal Heating
Solar Thermal Heating can be formed by creating a box with a glass cover with a dark or black back plate which is attached to pipes containing water. The glass lets light in and then traps the heat which is transferred to the back plate and in turn heats the pipes containing the water. The heated water is then pumped to a heat exchanger for use as hot water and heating.
Solar Thermal Engines
Curved mirrors can be used to focus the energy of the Sun onto a central area to heat water into steam which is in turn used to drive turbines and generate electricity.Solar Tube Water HeatingSolar tubes consist of an outer glass tube, a vacuum and an inner glass tube which has a fluid inside. The outer clear glass tube allows light in which then traps heat because of the vacuum and heats up the fluid in the inner tube which normally has a dark coating. As the fluid in the inner tube gets hot, it turns into a gas which rises to the top of the tube to in turn heat another pipe containing fluid. This pipe is then connected to a water tank where it transfers its heat to heat the water for residential use.
Solar Towers
Solar Towers are made up of many mirrors which focus sunlight onto a central tower. The sunlight heats salts to a very high temperature and this liquid molten salt is then used to heat water into steam to power turbines creating electricity. Concentrated Solar PowerIn concentrated solar power plants (CSP) curved mirrors are used to focus sunlight on a central pipe. Typically the sunlight can be concentrated to create temperatures of around 400 degrees centigrade in concentrated solar power troughs. The power troughs are designed to track the sun's position throughout the day to give the optimal power.
Passive Solar heating for buildings
By positioning buildings to face the sun in a particular direction and by using glass and thick insulating walls the Sun can be used to heat the interiors of buildings and reduce the need for conventional oil or gas heating systems.
Solar Furnace
A solar furnace using many moving mirrors called heliostats to focus sunlight onto a huge curved mirror. The curved mirror then focuses the sunlight onto a liquid filled collector. The liquid reaches temperatures of around 3800 degrees centigrade. This hot liquid in then pumped and the heat stored until it is need to heat water to create steam and drive turbines to create electricity.
Solar cells
Solar cells generate electrical energy from light energy- the photovoltaic effect. Solar cells are made from tiny slivers of silicon coated with a chemical dope. The surface of solar cells are designed to reflect as little light as possible and appear dark blue or black. Solar cells are connected together in series to create solar panel modules.
Solar cells create electricity since the sunlight causes electrons to jump from a positive layer in the panel to a negative layer – p-n junctions. When a circuit is created ,this causes a flow of electricity. To generate enough electricity to provide the annual power needs of an average UK house you would need solar panels taking up around 9 square metres on a south facing roof.
