How does Solar Energy Work / What do we mean by Solar Energy?
When we mention solar energy we usually refer to those technologies used in harnessing the energy of the sun for practical purposes.
The energy that reaches the Earth from the sun is enormous. The total reserves of energy that is stored in all of Earth’s reserves of fossil fuels like coal, petroleum, and natural gas are matched by only 20 days of sunshine.
-Photo to the left is by Bangun Rumah Persada.-
Solar energy technologies are classified into two broad categories depending on the way that they capture and convert sunlight into usable energy.
The first category is a passive solar collection technique. Passive solar technology has the advantage of reducing the need for alternative resources.
How does Solar Energy Work / Passive Solar Energy
When passive solar technology features are incorporated into the architecture of a building and are adjusted to fit the particular climate these methods can produce well lighted spaces that stay at comfortable temperatures reducing the need for power consuming artificial lighting and heating and cooling mechanisms.
How does Solar Energy Work / Active Solar Energy
Active solar energy is more technology oriented. These methods use photovoltaic cells that directly convert sunlight to electricity, which can then be used easily for almost any purpose.
Another technique used in active solar energy is solar thermal energy collection and concentration, which is the generation of heat energy by concentrating sunlight. Heat is also more readily usable because it can be used to generate steam or convection currents in air to turn turbines that generate electricity.
The biggest technological hurdle is harnessing this radiant energy to turn it into more readily usable forms of energy like heat or electrical energy. At the current level of our technology the highest efficiency that is attainable is probably only 15 to 20 percent. This small percentage constitutes a disadvantage to solar energy.
How does Solar Energy Work / The Nuts and Bolts
Generally the phrase “Solar Energy” refers to the conversion of solar radiation to other forms of practical energy like electricity or heat. However, the form of energy that is most usable to us is electricity. The generation of electricity from sunlight is further divided into to two sub categories. These methods are the direct and indirect methods.
Photovoltaic systems or solar cells are used to turn sunlight directly to electricity. Sunlight is made up of photons or particles of light energy. These photons have varying amounts of energy depending upon their wavelengths.
When a photon reaches the surface of a solar cell one of three things can happen. The photon may be reflected or it may pass through or it may be absorbed by the solar cell. The absorbed photon is the only one that can generate electricity.
If enough photons are absorbed by the semiconductor material that the solar cell is made out of, the energy of the photons dislodge an electron from the material. The material receives special treatment so that its surface is more favorable to free electrons. This treatment makes the electrons flow freely to the surface of the material.
How does Solar Energy Work / Opposites Attract
When enough electrons travel to the surface of the material with each electron carrying a negative charge there will be an imbalance that will exist between the front surface and the back surface of the material.
This imbalance becomes the voltage potential similar to the voltage potential between the positive and negative terminals of a battery. Connecting the two surfaces through a load will cause the electrons to flow creating a current. This is now electricity generated by solar radiation.
The indirect method uses solar power plants to generate electricity by using solar collectors to concentrate solar radiation and heat a liquid that produces steam. The steam that is produced is used to turn a turbine. This turbine is attached to a generator that finally produces electricity.
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