Solar Photovoltaic .

Solar Photovoltaic

http://www.makeitsolar.com/images/sunspot.gif

What is Sunlight?

http://www.lactamme.polytechnique.fr/Mosaic/images/SOLE.31.0512.D/image.jpg

How do Solar Cells Work?

Light (solar radiation) arrived on the earth in the form of energetic photons.

http://www.humanthermodynamics.com/sun-photon-diagram.jpg

Photons are powerful enough to knock electrons around

http://blueox.uoregon.edu/~karen/astro123/images/virtual_photons.gif

The Photoelectric Effect

Observed and Described 1839… by Becquerel, Hertz, and Thomson.Explained by Einstein 1905

http://en.wikipedia.org/wiki/Image:Us_pv_annual_may2004.jpg

What are Solar Cells Made Of?

http://www.howstuffworks.com/solar-cell.htm

Solar Cell Structure:

a. Encapsulateb. Contact Gridc. The Antireflective Coating (AR Coating)d. N-Type Silicone. P-Type Siliconf. Back Contact

http://www.specmat.com/Overview%20of%20Solar%20Cells.htm

Two Essential LayersA = n-type silicon (has free electrons)

B = p-type silicon (has free electron holes)

http://www.specmat.com/Overview%20of%20Solar%20Cells.htm

Sunlight knocks electrons from B to A.

• The electrons have to travel the circuit to get back to layer B.

http://www.corrosion-doctors.org/Solar/images/solarcell.jpg

Animation

http://www.teachersdomain.org/asset/psu06-e21_vid_pv4/

Practical Stuff• Solar Cells produce direct current (like regular

batteries)

A typical single crystal silicon PV cell of 100 cm2 will produce about 1.5 watts of power at 0.5 volts DC and 3

amps under full summer sunlight (1000Wm-2). http://www.corrosion-doctors.org/Solar/cells.htm

• Solar Cells are about 10 -25% efficient

• Power in Watts = Volts x Amperes

• Connecting cells in series increases voltage (additive) and keeps amperage constant

• Connecting cells in parallel increases amperage (additive) and keeps voltage constant

Need to configure panels to desired

voltage and amperage

http://windom.cybox.com/boat/systems/wiring/wind_solar.GIF

You need a regulator, storage battery, DC AC converter

http://www.howstuffworks.com/solar-cell6.htm

http://en.wikipedia.org/wiki/File:Us_pv_annual_may2004.jpg

How much does it cost?

“To give you an idea of how much a house system would cost, let's consider the Solar House -- a model residential home in Raleigh, North Carolina, with a PV system set up by the North Carolina Solar Center to demonstrate the technology. It's a fairly small home, and it is estimated that its 3.6-kW PV system covers about half of the total electricity needs (this system doesn't use batteries -- it's connected to the grid). Even so, at $9 per Watt, this installed system would cost you around $32,000. “

http://www.howstuffworks.com/solar-cell7.htm

Vidoeshttp://video.nytimes.com/video/2007/07/06/business/1194817104324/possibilities-in-solar-

energy.html?scp=3&sq=solar&st=cse

5:56

http://renergycafe.com/political/obama-our-renewable-energy-future/Obama’s Energy Campaign Speech 13:19

http://thisweekwithbarackobama.blogspot.com/2009/02/obama-speaks-at-department-of-energy.htmlObama 8 min