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OverviewOverview

History of PhotovoltaicsHistory of Photovoltaics

Photovoltaic effect vs. Photoelectric effectPhotovoltaic effect vs. Photoelectric effect

Semiconductor productionSemiconductor production

P-N junctionP-N junction

Different types of PV cells and the efficienciesDifferent types of PV cells and the efficiencies

A brief look at the future of solar energyA brief look at the future of solar energy

What is Solar Energy What is Solar Energy and How is it used?and How is it used?Radiation from sunRadiation from sun

• Earth receives ~174 petawatts (10Earth receives ~174 petawatts (1015 15 watts) at watts) at the upper atmosphere. Only ~ 47% is the upper atmosphere. Only ~ 47% is absorbed.absorbed.

• Solar panelsSolar panels

PhotosynthesisPhotosynthesis

History of PhotovoltaicsHistory of Photovoltaics

18391839 French scientist Edmond Becquerel French scientist Edmond Becquerel discovers the photovoltaic effectdiscovers the photovoltaic effect

18831883 The first solid state photovoltaic cell was The first solid state photovoltaic cell was built by Charles Frittsbuilt by Charles Fritts

19051905 Albert Einstein published his paper on the Albert Einstein published his paper on the photoelectric effectphotoelectric effect

19541954 The first practical photovoltaic was The first practical photovoltaic was developed at Bell Laboratories developed at Bell Laboratories

1970’s1970’s Solar energy became commercializedSolar energy became commercialized

20122012 World record efficiency reached 44% with a World record efficiency reached 44% with a multijunction cellmultijunction cell

Photovoltaic Effect vs. Photovoltaic Effect vs. Photoelectric EffectPhotoelectric Effect

Photovoltaic EffectPhotovoltaic Effect Photoelectric EffectPhotoelectric Effect

• The creation of voltage or electrical current in a material upon exposure to light.

• Electrons absorb energy and become excited.

• Electrons move to the conduction band to become free.

• The emission of electrons from a solid, liquid, or gas upon exposure to light.

• Electrons are ejected when excess energy is absorbed.

• If the photon energy is too low the electrons will not be able to escape

DopingDoping

• A process first developed by John Robert A process first developed by John Robert WoodyardWoodyard

• Doping intentionally introduces impurities into a Doping intentionally introduces impurities into a pure semiconductor for the purpose of pure semiconductor for the purpose of modulating its electrical propertiesmodulating its electrical properties

• Group IV semiconductors such as Silicon are Group IV semiconductors such as Silicon are usedused

• By doping semiconductors the we are able to By doping semiconductors the we are able to form P-type and N-type semiconductors form P-type and N-type semiconductors

P-type SemiconductorP-type Semiconductor

• Doped with Group III Doped with Group III element such as Boronelement such as Boron

• Abundance of holes or Abundance of holes or electron deficiencieselectron deficiencies

• Electrical conduction Electrical conduction due primarily due primarily movement of holesmovement of holes

N-type SemiconductorN-type Semiconductor

• Doped with Group V Doped with Group V elements such as elements such as PhosphorousPhosphorous

• Abundance of extra Abundance of extra electronselectrons

• Electrical conduction Electrical conduction due primarily to due primarily to movement of electronsmovement of electrons

P-N JunctionP-N Junction

Thin-film Solar CellsThin-film Solar Cells• Around 8% efficiencyAround 8% efficiency

• Very thin layers of Very thin layers of photovoltaic material. photovoltaic material. The thickness is The thickness is anywhere between a few anywhere between a few nanometers to tens of nanometers to tens of micrometersmicrometers

• Small portion of the Small portion of the solar cell market solar cell market

Polycrstalline Solar CellsPolycrstalline Solar Cells• Around 14-16 % Around 14-16 %

efficiencyefficiency

• Uses multiple crystal to Uses multiple crystal to harness the suns light.harness the suns light.

• Generally, these are Generally, these are cheaper and easier to cheaper and easier to install. install.

Monocrystalline Solar Monocrystalline Solar CellsCells• Around 16-19 % Around 16-19 %

efficiencyefficiency

• Made from a single Made from a single crystal cellcrystal cell

• Generally, these are the Generally, these are the most popular and most most popular and most efficient cells on the efficient cells on the market. market.

Multijunction CellsMultijunction Cells• Efficiencies up to 44 %Efficiencies up to 44 %

• Not available on the market. Only used experimentally in a lab Not available on the market. Only used experimentally in a lab setting.setting.

• Cells are used in tandem to gain better efficiencies Cells are used in tandem to gain better efficiencies

Solar Cell Efficiencies Solar Cell Efficiencies

Solar Cell DiagramSolar Cell Diagram• Each cell produces 0.5 VoltsEach cell produces 0.5 Volts

• Cells are connected in series Cells are connected in series of 18 Volts, which of 18 Volts, which creates a module of 36 cellscreates a module of 36 cells

• A photovoltaic system needs A photovoltaic system needs an array of cells, charge an array of cells, charge controller, battery system, an controller, battery system, an inverter, and wires to connect inverter, and wires to connect the systemthe system

Future for Solar EnergyFuture for Solar Energy• Over the last 20 years, prices have Over the last 20 years, prices have

dropped significantlydropped significantly

• Clean renewable energyClean renewable energy

• Production has increase Production has increase exponentiallyexponentially

• Dye-sensitized solar cell (DCS) Dye-sensitized solar cell (DCS) technology technology

• Many other examples Many other examples

References References ““Brown, Eric W. "An Introduction to Solar Energy." N.p., n.d. Web. 6 Apr. 2013.Brown, Eric W. "An Introduction to Solar Energy." N.p., n.d. Web. 6 Apr. 2013.

Future Energy.” – Future Energy.” – Concepts for Future Electricity Generation.Concepts for Future Electricity Generation. Web. 12 Apr. 2013. Web. 12 Apr. 2013.

Honsburg, Christiana, and Stuart Bowden. "The Photovoltaic Effect." PVEducation. N.p., n.d. Web. 11 Apr. Honsburg, Christiana, and Stuart Bowden. "The Photovoltaic Effect." PVEducation. N.p., n.d. Web. 11 Apr. 2013.2013.

““How Does Solar Power Work?” How Does Solar Power Work?” Solar Power.Solar Power. Web. 2 Apr. 2013 Web. 2 Apr. 2013

Marti, Antonio, and A. Luque. "Thermodynamics of Solar Energy Conversion.” Next Generation Photovoltaics: Marti, Antonio, and A. Luque. "Thermodynamics of Solar Energy Conversion.” Next Generation Photovoltaics: High Efficiency through Full Spectrum High Efficiency through Full Spectrum Utilization. Bristol: Institute of Physics, 2004. SciFinder. Web. 19 Utilization. Bristol: Institute of Physics, 2004. SciFinder. Web. 19 Mar. 2013.Mar. 2013.

Miessler, Gary L., and Donald A. Tarr. “The Crystalline Solid State.” Miessler, Gary L., and Donald A. Tarr. “The Crystalline Solid State.” Inorganic Chemistry.Inorganic Chemistry. 4 4thth ed. Upper Saddle ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2011. 238-239. Print.River, NJ: Pearson Prentice Hall, 2011. 238-239. Print.

Moore, Taylor; "Opening the Door for Utility Photovoltaics", EPRI Journal, Jan./Feb. 1987; Palo Alto, CA; 1987Moore, Taylor; "Opening the Door for Utility Photovoltaics", EPRI Journal, Jan./Feb. 1987; Palo Alto, CA; 1987

"Solar Cell Efficiency." NREL. National Renewable Energy Laboratory, n.d. Web. 02 Apr. 2013."Solar Cell Efficiency." NREL. National Renewable Energy Laboratory, n.d. Web. 02 Apr. 2013.

"Types of Solar Panels." Sun Connect. N.p., n.d. Web. 05 Apr. 2013."Types of Solar Panels." Sun Connect. N.p., n.d. Web. 05 Apr. 2013.

Zyga, Lisa. “Solar Thermal Process Produces Cement with No Carbon Dioxide Emissions.” Zyga, Lisa. “Solar Thermal Process Produces Cement with No Carbon Dioxide Emissions.” Science News, Science News, Technology, Physics, Nanotechnology, Space Science, Earth Science, Medicine.Technology, Physics, Nanotechnology, Space Science, Earth Science, Medicine. Phys.Org, 10 Apr. 2012. Phys.Org, 10 Apr. 2012. Web. 2 Apr. 2013Web. 2 Apr. 2013

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