How is solar power used to generate electricity? how does it work?
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Answer:
There are two processes. Phot voltaic cells (aka solar cells) work by absorbing radiant energy. This excites electrons in the absorbing medium (usually silicon). These excited electrons can be made to flow through a closed conducting circuit producing electricity. The cells are fairly efficient, but they produce direct current. Unfortunately, DC cannot be transmitted over long distances so power produced by solar cells needs to be used close by. Also, most power users are actually designed to use alternating current so even for local use the DC must be converted to AC via a device known as an inverter. All of this adds to the cost making solar cells uneconomic absent some form of subsidy.
The other approach would be to focus sunlight (using mirrors) on a boiler to generate high pressure steam. This steam can then be used to drive generators via turbines in the same way as steam generated in fuel fired power plants.
A demonstration plant using this approach was actually built in the U.S. and actually produced about 1MW of power. The ecological foot print of this type of generating facility is, however, as it requires a very large area.
Both approaches produce no energy at night and power production is greatly reduced when its cloudy.
Light contains photons which create a flow of electricity in solar cells, which store that flow (or energy) and can spit it back out in the form of voltage and current (or power).
It can also be concentrated by use of mirrors or lenses to run a steam or stirling cycle.
solar cells are alright but not the killer solution everyone thinks they are. Solar water heating is cheap and effective though. Dont think the systems costs a lot. Think batch heating, look it up.
Two ways, both of which have been used. One way is to concentrate sunlight on a tank containing water which is heated to create steam which runs a turbine; there is an example of such a facility in southern California (although I have heard that it has been shut down). The other way is to use photovoltaic cells, in which silicon wafers, appropriately doped to create diodes, are exposed to sunlight. Photons can knock electrons from the ground state to an energized state, and they have to flow through an external circuit to return to the ground state. The current can be used to charge a battery, or (after conversion to AC by suitable equipment) be put out onto power lines. Photovoltaic cells are not very efficient (11% is typical), and are quite costly: one watt worth of solar cells costs about $10, and can produce at most 2 kWh of electricity per year, worth about 25 cents. Hence they are not economical unless a subsidy can be obtained.
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