Solution: Solar EnergyEdit
Since most renewable energy is ultimately "solar energy" this term is slightly confusing and used in two different ways: firstly as a synonym for "renewable energies" as a whole and secondly for the energy that is directly collected from sunlight. In this section it is used in the latter category. Solar power can be used to:
- generate electricity using solar cells
- generate electricity using concentrated solar power
- generate electricity by heating trapped air which rotates turbines in a solar chimney.
- heat buildings, directly. Careful positioning of windows and use of brises soleil can maximise inflow of light at the times it is most needed, heating the building while preventing overheating during midday and summer.
- heat buildings, through heat pumps
- heat foodstuffs, through solar ovens.
- heat water for domestic consumption and heating using rooftop solar panels.
Obviously the sun does not provide constant energy to any spot on the Earth, so its use is limited. Solar cells are often used to power batteries, as most other applications would require a secondary energy source, to cope with outages. Some homeowners use a solar system which sells energy to the grid during the day, and draw energy from the grid at night; this is to everyone's advantage, since power demand for air conditioning is highest during the day.
Problems generally associated with electricity from solar cells:
- It is not available in dark or cloudy conditions, hence producing variable voltages.
- Solar panels are expensive and energy collection is not yet optimized.
- The current generated is only of DC type. It must be converted to AC current before transmission.
Concentrated solar power plants work best in hot deserts and other places with plenty of direct sunshine. There are methods for storing solar heat so that electricity generation may continue through the night and even on cloudy days. (http://en.wikipedia.org/wiki/Renewable_energy)
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