Solar Energy

Solar Energy

By Jason C, Brad S

June 5th, 2012

A very widespread and effective way to generate electricity is by harnessing the sun’s power and converting it into electricity. This alternative is very desirable: every minute, enough energy in the form of sunlight arrives on the earth to meet our energy demands for an entire year – the only problem is we cannot harness all of it – yet. The main way to generate electricity is by using photovoltaic cells – these are the bluish colored cells seen in everything from calculators to rooftops of homes.

A small solar cell.

Physics Concepts

Photovoltaic or solar cells generate power by converting light to electricity at an atomic level: the photoelectric effect is responsible for this. In a solar cell, a thin layer of a semiconductor is treated and gains an electric field. This means that the semiconductor is positive on one side and negative on the other. When light (photons) strikes this semiconductor material, electrons are knocked loose and can form an electric current if passed through a circuit. The result is the generation of electricity. The current produced by a photoelectric array is directly proportional to the amount of light that strikes array; the voltage will remain the same as each cell is designed to a specification of voltage generated.

The basis for operation of the Photovoltaic cell is the photoelectric effect. From a high-level view, the photoelectric effect is very simple: light goes in, electrons come out. What happens here is the light photon strikes a certain material, giving energy to the electrons of the material (similar to a collision, photons act as particles). The electrons then have enough energy to free themselves from the material, and fly away. These electrons can now be made to flow in a circuit, generating electricity.

Illustration of the Photoelectric Effect : Ejection of Electrons

In order to generate a lot of electricity, Photovoltaic cells are often combined in large amounts, forming a solar panel.  These solar panels can be placed on a rooftop, and can then be connected directly to a battery or appliance.

A Solar Panel mounted on a household rooftop.

Social Impacts

Further development and use of solar energy would be able to make a huge positive impact on society. Compared to currently widespread methods of electricity generation, such as the burning of fossil fuels, solar power is far more sustainable. The earth has a limited supply of fossil fuels, while the sun will continue to give humans energy for many millions of years to come. Burning fossil fuels creates a large amount of pollution, reducing air quality and contributing to increased carbon dioxide levels in the atmosphere, while active solar cells produce none of this. Solar cells also require less water to make than other methods of electricity generation do to function. While some people think that solar cells are inefficient in that they require more energy to produce than they themselves produce, modern solar cells ‘break even’ in energy after six months to two years of use, and continue to generate energy for many more years. Solar cells will soon have a large impact on society. Homes and businesses will have solar cells on roofs and windows, and large solar plants are likely to be set up in deserts. Despite the general lack of knowledge about solar power, and the initial cost of the cells, in the not too distant future, solar power will be a very large part of how we as a society generate energy, and it will be good for us as well as the earth.

 References

NASA Science : Photoelectrics. Retrieved June 5th, 2012, http://science.nasa.gov/science-news/science-at-nasa/2002/solarcells/.

Photoelectric Effect, retrieved June 5th, 2012 http://physics.bu.edu/~duffy/PY106/PhotoelectricEffect.html .

Scribd: Environmental and Social impact of Solar Photovoltaics, retrieved June 5th, 2012,

http://www.scribd.com/doc/34182066/Environmental-and-Social-Impact-of-Solar-Photovoltaics

Photo References

http://gomakesolarpanels.com/wp-content/uploads/2011/06/Solar-Panel-Electricity.jpg

http://www.physicsforums.com/mgc_gloss/30/img_1.png

http://upload.wikimedia.org/wikipedia/commons/9/90/Solar_cell.png

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