Photovoltaic cell - Revision history

Jmdonev: 1 revision imported

2021-12-20T19:47:17Z

1 revision imported

← Older revision	Revision as of 19:47, 20 December 2021
(No difference)

energy>Jmdonev at 21:31, 9 December 2021

2021-12-09T21:31:22Z

← Older revision		Revision as of 21:31, 9 December 2021
Line 1:		Line 1:
	[[Category:Done ~~2018~~-06-15]]		[[Category:Done 2021-10-29]]
	[[Category: Translated to French]]		[[Category: Translated to French]]
			[[Category:Done 2021-10-29]]
			[[Category:Translated to Spanish]]
	[[fr:Cellule photovoltaïque]]		[[fr:Cellule photovoltaïque]]
			[[es:Célula fotovoltaica]]
	[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]		[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]

Line 17:		Line 20:
	==Solar Cell Efficiency==		==Solar Cell Efficiency==
	:: [[solar cell efficiency\|''main article'']]		:: [[solar cell efficiency\|''main article'']]
	[[Efficiency]] is a design concern for photovoltaic cells, as there are many factors that limit their efficiency. The main factor is that 1/4 of the [[solar energy to the Earth]] cannot be converted into electricity by a silicon semiconductor. The physics of semiconductors requires a minimum [[photon]] energy to remove an [[electron]] from a crystal structure, known as the '''band-gap energy'''. If a photon has less energy than the band-gap, the photon gets absorbed as [[thermal energy]]. For [[silicon]], the band-gap energy is 1.12 [[electron volt]]s.<ref name=Wolfson>R. Wolfson, "Photovoltaic Solar Energy" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 9, sec. 5, pp. 244-252</ref> Since the energy in the photons from the [[sun]] cover a wide range of energies, some of the incoming energy from the Sun does not have enough energy to knock off an electron in a silicon PV cell. Even from the light that ''can'' be absorbed, there is still a problem. Any energy ''above'' the band-gap energy will be transformed into [[heat]]. This also cuts the efficiency because that heat energy is not being used for any useful task.<ref name=Wolfson/> Of the electrons that are made available, not all of them will actually make it to the metal contact and generate electricity. ~~This is because some of them~~ will not be accelerated sufficiently by the voltage inside the semiconductor. ~~Because of the reasons listed, the~~ theoretical efficiency of silicon PV cells is about '''33%'''.<ref name=Wolfson/>		[[Efficiency]] is a design concern for photovoltaic cells, as there are many factors that limit their efficiency. The main factor is that 1/4 of the [[solar energy to the Earth]] cannot be converted into electricity by a silicon semiconductor. The physics of semiconductors requires a minimum [[photon]] energy to remove an [[electron]] from a crystal structure, known as the '''band-gap energy'''. If a photon has less energy than the band-gap, the photon gets absorbed as [[thermal energy]]. For [[silicon]], the band-gap energy is 1.12 [[electron volt]]s.<ref name=Wolfson>R. Wolfson, "Photovoltaic Solar Energy" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 9, sec. 5, pp. 244-252</ref> Since the energy in the photons from the [[sun]] cover a wide range of energies, some of the incoming energy from the Sun does not have enough energy to knock off an electron in a silicon PV cell. Even from the light that ''can'' be absorbed, there is still a problem. Any energy ''above'' the band-gap energy will be transformed into [[heat]]. This also cuts the efficiency because that heat energy is not being used for any useful task.<ref name=Wolfson/> Of the electrons that are made available, not all of them will actually make it to the metal contact and generate electricity. Some electrons will not be accelerated sufficiently by the voltage inside the semiconductor to leave the system. These effects combine to create a theoretical efficiency of silicon PV cells is about '''33%'''.<ref name=Wolfson/>

	There are ways to improve the efficiency of PV cells, all of which come with an increased cost. Some of these methods include increasing the purity of the semiconductor, using a more efficient semiconducting material such as Gallium Arsenide, by adding additional layers or p-n junctions to the cell, or by concentrating the Sun's energy using [[concentrated photovoltaics]]. On the other hand, PV cells will also degrade, outputting less energy over time, due to a variety of factors including UV exposure and weather cycles. A comprehensive report from the National Renewable Energy Laboratory (NREL) states that the median degradation rate is 0.5% per year.<ref>Dirk C. Jordan and Sarah R. Kurtz. ''Photovoltaic Degradation Rates — An Analytical Review'', National Renewable Energy Laboratory, USA, 2012. Accessed April 24, 2018. [Online] Available at https://www.nrel.gov/docs/fy12osti/51664.pdf</ref>		There are ways to improve the efficiency of PV cells, all of which come with an increased cost. Some of these methods include increasing the purity of the semiconductor, using a more efficient semiconducting material such as Gallium Arsenide, by adding additional layers or p-n junctions to the cell, or by concentrating the Sun's energy using [[concentrated photovoltaics]]. On the other hand, PV cells will also degrade, outputting less energy over time, due to a variety of factors including UV exposure and weather cycles. A comprehensive report from the National Renewable Energy Laboratory (NREL) states that the median degradation rate is 0.5% per year.<ref>Dirk C. Jordan and Sarah R. Kurtz. ''Photovoltaic Degradation Rates — An Analytical Review'', National Renewable Energy Laboratory, USA, 2012. Accessed April 24, 2018. [Online] Available at https://www.nrel.gov/docs/fy12osti/51664.pdf</ref>

Jmdonev: 1 revision imported

2021-09-27T00:02:52Z

1 revision imported

← Older revision	Revision as of 00:02, 27 September 2021
(No difference)

energy>Ethan.boechler at 19:28, 10 September 2021

2021-09-10T19:28:30Z

← Older revision		Revision as of 19:28, 10 September 2021
Line 1:		Line 1:
	[[Category:Done 2018-06-15]]		[[Category:Done 2018-06-15]]
			[[Category: Translated to French]]
			[[fr:Cellule photovoltaïque]]
	[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]		[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]

Jmdonev: 1 revision imported

2018-06-25T14:30:28Z

1 revision imported

← Older revision	Revision as of 14:30, 25 June 2018
(No difference)

Jmdonev at 00:28, 9 June 2018

2018-06-09T00:28:26Z

Show changes

J.williams: 1 revision imported

2015-09-18T16:52:04Z

1 revision imported

← Older revision	Revision as of 16:52, 18 September 2015
(No difference)

Jhanania at 23:42, 4 September 2015

2015-09-04T23:42:54Z

← Older revision		Revision as of 23:42, 4 September 2015
Line 1:		Line 1:
	[[Category:Done 2015-09-05]]		[[Category:Done 2015-09-06]]
	[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]		[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]

	<onlyinclude>A '''photovoltaic cell''' ('''PV cell''') is an [[energy]] harvesting technology, that converts [[solar energy]] into useful [[electricity]]. The vast majority are silicon [[semiconductor]]s, and interact with incoming [[photon]]s in order to generate an electric [[current]].</onlyinclude>		<onlyinclude>A '''photovoltaic cell''' ('''PV cell''') is an [[energy]] harvesting [[technology]], that converts [[solar energy]] into useful [[electricity]]. The vast majority are silicon [[semiconductor]]s, and interact with incoming [[photon]]s in order to generate an electric [[current]].</onlyinclude>

	==Operation==		==Operation==
	The physics of semiconductors requires a minimum [[photon]] energy an electron from a crystal structure, known as the '''band-gap energy'''. If photon has less energy than the band-gap, the photon gets absorbed as [[thermal energy]]. For silicon, the band-gap energy is 1.12 [[electron volt]]s.<ref name=Wolfson>R. Wolfson, "Photovoltaic Solar Energy" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 9, sec. 5, pp. 244-252</ref> Since the energy in the photons from the sun cover a wide range of energies, some of the incoming energy from the Sun does not have enough energy to knock off an electron in a silicon PV cell. The longest [[wavelength]] (which corresponds to the lowest energy) that is capable removing the is 1.1 [[prefixes\|µ]][[meter\|m]],<ref><m>\lambda=\frac{hc}{E}=\frac{(6.626kg*m^2/s) \times (3\times10^8 m/s)}{1.12eV}\times \frac{1eV}{1.6\times10^{-19}J}=1.1\mu m</m></ref> this means that ~1/4 of the light from the Sun does not sufficient enough to create electricity.<ref name=Wolfson/>		The physics of semiconductors requires a minimum [[photon]] energy to remove an [[electron]] from a crystal structure, known as the '''band-gap energy'''. If photon has less energy than the band-gap, the photon gets absorbed as [[thermal energy]]. For [[silicon]], the band-gap energy is 1.12 [[electron volt]]s.<ref name=Wolfson>R. Wolfson, "Photovoltaic Solar Energy" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 9, sec. 5, pp. 244-252</ref> Since the energy in the photons from the [[sun]] cover a wide range of energies, some of the incoming energy from the Sun does not have enough energy to knock off an electron in a silicon PV cell. The longest [[wavelength]] (which corresponds to the lowest energy) that is capable removing the is 1.1 [[prefixes\|µ]][[meter\|m]],<ref><m>\lambda=\frac{hc}{E}=\frac{(6.626kg*m^2/s) \times (3\times10^8 m/s)}{1.12eV}\times \frac{1eV}{1.6\times10^{-19}J}=1.1\mu m</m></ref> this means that ~1/4 of the light from the Sun does not sufficient enough to create electricity.<ref name=Wolfson/>

	[[File:pvcellop.gif\|500px\|center\|Figure 2. The basic operation of a PV cell.<ref>Wikimedia Commons [Online], Available: http://upload.wikimedia.org/wikipedia/commons/7/7d/Operation_of_a_basic_photovoltaic_cell.gif</ref>]]		[[File:pvcellop.gif\|500px\|center\|Figure 2. The basic operation of a PV cell.<ref>Wikimedia Commons [Online], Available: http://upload.wikimedia.org/wikipedia/commons/7/7d/Operation_of_a_basic_photovoltaic_cell.gif</ref>]]

	The specific semiconductors used are called [[p-n junction]]s, which essentially work by creating an internal [[electric field]] due to an uneven distribution of [[charge]]s. The [[voltage]] each cell creates is about 0.6 V, which is relatively small. When photons knock an electron free from its atomic shell, it ''can'' flow through this voltage (but won't always, see '''Efficiency''' below) and flow to a metal contact which can be connected to an external [[electric circuit]]. The PV cell is essentially a solar-powered [[battery]], causing a current to flow just like a chemical battery would.<ref name=Wolfson/>		The specific semiconductors used are called [[p-n junction]]s, which essentially work by creating an internal [[electric field]] due to an uneven distribution of [[charge]]s. The [[voltage]] each cell creates is about 0.6 V, which is relatively small. When photons knock an electron free from its atomic shell, it ''can'' flow through this voltage (but won't always, see '''Efficiency''' below) and flow to a [[metal]] contact which can be connected to an external [[electric circuit]]. The PV cell is essentially a solar-powered [[battery]], causing a current to flow just like a chemical battery would.<ref name=Wolfson/>

	==Efficiency==		==Efficiency==

J.williams: 1 revision imported

2015-09-03T18:22:51Z

1 revision imported

← Older revision	Revision as of 18:22, 3 September 2015
(No difference)

Jmdonev at 23:41, 28 August 2015

2015-08-28T23:41:26Z

← Older revision		Revision as of 23:41, 28 August 2015
Line 1:		Line 1:
	[[Category:Done 2015-06-11]]		[[Category:Done 2015-09-05]]
	[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]		[[File:pvcell.jpg\|300px\|thumb\|Figure 1. A solar panel, consisting of many photovoltaic cells.<ref>"20110504-RD-LSC-0621 - Flickr - USDAgov" by U.S. Department of Agriculture. Licensed under CC BY 2.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg#/media/File:20110504-RD-LSC-0621_-_Flickr_-_USDAgov.jpg</ref>]]

Line 9:		Line 9:
	[[File:pvcellop.gif\|500px\|center\|Figure 2. The basic operation of a PV cell.<ref>Wikimedia Commons [Online], Available: http://upload.wikimedia.org/wikipedia/commons/7/7d/Operation_of_a_basic_photovoltaic_cell.gif</ref>]]		[[File:pvcellop.gif\|500px\|center\|Figure 2. The basic operation of a PV cell.<ref>Wikimedia Commons [Online], Available: http://upload.wikimedia.org/wikipedia/commons/7/7d/Operation_of_a_basic_photovoltaic_cell.gif</ref>]]

	The specific semiconductors used are called [[pn junction]]s, which essentially work by creating an internal [[electric field]] due to an uneven distribution of [[charge]]s. The [[voltage]] each cell creates is about 0.6 V, which is relatively small. When photons knock an electron free from its atomic shell, it ''can'' flow through this voltage (but won't always, see '''Efficiency''' below) and flow to a metal contact which can be connected to an external [[electric circuit]]. The PV cell is essentially a solar-powered [[battery]], causing a current to flow just like a chemical battery would.<ref name=Wolfson/>		The specific semiconductors used are called [[p-n junction]]s, which essentially work by creating an internal [[electric field]] due to an uneven distribution of [[charge]]s. The [[voltage]] each cell creates is about 0.6 V, which is relatively small. When photons knock an electron free from its atomic shell, it ''can'' flow through this voltage (but won't always, see '''Efficiency''' below) and flow to a metal contact which can be connected to an external [[electric circuit]]. The PV cell is essentially a solar-powered [[battery]], causing a current to flow just like a chemical battery would.<ref name=Wolfson/>

	==Efficiency==		==Efficiency==