Wednesday, 11/19/2008

The Basics of Solar Power

Solar power is the harnessing of the sun’s heat and light emissions. It is the power we get from converting the sun’s energy. The energy of the sun is abundant, clean, and environment friendly. Every day, we receive more energy from the sun than could be used by us, globally, in 27 years! Solar power is considered to be renewable as the energy from the sun is estimated to last another 4.5 billion years.

The basic difference between generation of solar power and the conventional power is:

• Solar Power does not need large, polluting power stations

• Solar power can be generated at home and in industries

• Once installed, there is no further need of any raw materials to generate solar power, except sunlight

Converting Sun’s Energy

There are many different ways of converting the sun’s energy, in the form of light, into electricity.

Photovoltaic Cells – These are more commonly known as solar cells and are made of semi-conductors. These energy converters convert the energy of the sunlight into electricity. Sunlight, which is a stream of energy particles – photons – falls on the semi-conductors or the conductors, and transfers its energy to them. The photons transfer their energy on hitting the silicon atoms in the solar cells, thereby releasing the electrons from their orbit around the nucleus, generating electricity.

To help concentrate the sunlight on a small area of photovoltaic cells, Fresnel lenses, mirrors, and mirrored dishes are used as concentrators. A Fresnel lens consists of concentric rings of segmental lenses having a short focal length. Multiple solar cells are combined to make a solar panel. For protection of these solar cells, glass, with an anti-reflective coating, is used as a cover.

Solar panels usually produce 12V or 24V DC power.

Boiling Fluids – Mirrors or reflective surfaces are used to concentrate the sun's energy on a fluid reservoir. This leads to steam generation, by boiling of the fluid, which in turn spins a turbine, to generate electricity. Using a turbine to generate electricity is similar to the conventional way of power generation, except that solar energy is used in place of burning raw materials.

Either DC or AC electric power can be generated.

Heat Engine – The heat engine, the most common one being a Stirling engine, has a gas enclosed compartment. Through mirrors or reflective surfaces, the sunlight is concentrated on the engine, which heats up the gas. This causes the piston to move to run the generator. The gas gets cooled and returns to go through the heating cycle again. These heat engines are noiseless, and depending on the generator, can produce either DC or AC current.

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