photocells and solar cells

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sipple
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photocells and solar cells

Postby sipple » Mon May 24, 2004 3:54 pm

could someone please tell me what the difference is between a photocell and a solar cell. thanks

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dkruss
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Postby dkruss » Mon May 24, 2004 10:15 pm

They are fundamently the same thing. Solarcells are called solarcells because they are designed to collect solar energy. Photocells are small devices that are used for purposes other than collecting solar energy where the intensity of light is needed to be measured.

An example of a use of a photocell is to control street lights, which you only want to come on when there minimal daylight.

sipple
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Postby sipple » Tue May 25, 2004 2:44 pm

could u please explane if the use of the photoelectri effect is the same in solar cells and photocells. if there not the same then how r they different? thanks

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dkruss
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Postby dkruss » Tue May 25, 2004 9:14 pm

The photoelectric effect is a different process to that of a solar/photo cell.

For the photoelectric effect, have a look at Prof Wolfe's notes here http://www.phys.unsw.edu.au/~jw/1231/quantum.pdf

Things a different in solar/photo cells. In a photocell we ususally have a semiconductor junction that when you shine light on to it, you create electron-hole pairs by exciting electrons from a low energy level (called a valence band) to an higher energy level (called conduction band) in which they conduct. The energy difference between the levels is called the "bandgap energy'

A solar cell is just a semiconductor in which the bandgap energy is chosen to be near the energy of sunlight (remember for light, energy= (Planks const * speed of light)/wavelength. The area of the junction is many times larger than that of a photocell and thus when a circuit is formed you have a current flow.

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joe
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Postby joe » Wed May 26, 2004 10:25 am

dkruss' replies are good.

The photoelectric and photovoltaic effects are discussed and compared on the high school physics FAQ, which is at

http://www.phys.unsw.edu.au/~jw/FAQ.html

It has some links to further material.

Best
Joe

CorneliusLarson
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Re:

Postby CorneliusLarson » Tue Jan 14, 2014 8:44 pm

dkruss wrote:They are fundamently the same thing. Solarcells are called solar kits because they are designed to collect solar energy. Photocells are small devices that are used for purposes other than collecting solar energy where the intensity of light is needed to be measured.

An example of a use of a photocell is to control street lights, which you only want to come on when there minimal daylight.

Ok nice.. Do you have more points to elaborate the difference? I am working on similar topic of my college level project.
Last edited by CorneliusLarson on Thu Jan 16, 2014 2:46 am, edited 1 time in total.

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joe
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Re: photocells and solar cells

Postby joe » Wed Jan 15, 2014 7:00 am

Solar panels are large, so as to capture lots of energy. They are made of lots of diodes in series and parallel combinations. Photocells only need the signal, so may be small. They often have just a single diode or transistor.

Joe


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