Transcript Basic Science and Modeling of Solar Energy

Basic Science and Modeling
of
Solar Energy
by
Jeremy Parra and Sandrio Elim
SCI 322U – Energy and Society II Presentation
By Jeremy Parra and Sandrio Elim
1
Topics:
• Science of Solar Energy
• Technology Using Solar Energy
SCI 322U – Energy and Society II Presentation
By Jeremy Parra and Sandrio Elim
2
Science of Solar Energy
•Resources:
•Energy Flows:
•Chemistry and Physics background:
SCI 322U – Energy and Society II Presentation
By Jeremy Parra and Sandrio Elim
3
“The pp-chain (proton-proton chain) involves a series of nuclear
reactions that are responsible for the generation of energy in the sun. The
basis for the suns energy is that four hydrogen atoms fuse to form one
helium atom whose mass is slightly less than the mass of the combined
four hydrogen atoms. The missing mass is what was converted to energy.
“In the pp-chain, two protons (moving at very fast velocities) fuse
together to create deuterium. A neutrino and a positron are expelled in
the process. Deuterium (one proton and one neutron) fuse with one more
proton creating Helium-3. A photon is released in this process and this is
what gives the sun it's energy. After Helium-3 is created, it fuses with
another of its type and 2 hydrogen atoms are expelled. The result is one
atom of Helium-4 and 2 atoms of Hydrogen to start the process all over
again. Even though the photons are accountable for most of the sun's
energy, about 5% of the energy is given off in neutrinos.”
-bib. 1
Solar fusion
Fig. 1 (copied ,bib.1)
Hydrogen
Hydrogen(one proton)
H
electron
Deuterium
neutrino
positron
Deuterium(one proton one neutron)
2
H
electron
γ
Helium
photon
Helium(two protons one neutron)
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He
Yield
H
3
He
H
Sun Light
Photon
If when a photon strikes an electron it has
the amount of energy to break the electronelectron bond( band gap) a free electron will
result.
This results in a positive “hole” and a
negative electron.
Photon
Free electron
Hole
Semiconductors
 A semiconductor has electrical conductivity greater
that insulators but less than good conductors.
 Silicon has four valence electrons.
 Pure silicon is in a perfect state of valence(has no
free electrons).
Si
Silicon
electrons
nucleus
hole
Free electron
Semiconductors
 When phosphorous is substituted for a silicon atom,
there is one electron left
 The remaining electron is very loosely bound by the
slightly more positive charge of the nucleus of the
phosphorous atom.
 This electron travels easily around the phosphorous
atom.
 Silicon that contains a large number of atoms with an
extra valence electron is called n type silicon (n is for
negative).
N-Type
Extra Electron
Si
Si
Si
P
Si
Si
Si
Si
Semiconductors
 If a boron atom is substituted for a silicon atom, there
is one valence electron which has no partner.
 This missing electron is a hole.
 This yields a positive charge (the absence of an
negative electron).
 This is a p-type
P-Type
Hole
Si
Si
B
Si
Si
Si
 The binding force of electron pairs is much stronger than
the electromagnetic force between an electron and the
nucleus
 The extra electron moves from the n-type to the p-type
 And these electrons form valence pairs with the electrons
that were missing a pair
 This results in a shift in charge that creates an electric field
in the material.
 Now the n-side(doped with phosphorus) gains a positive
charge.
 When the electron moved it left a proton
 “Similarly, the boron atom is surrounded by one more
electron than there are positive protons in the boron
nucleus.”
 The n-type side doped with Phosphorus easily lends its
free electron to the positive side (doped with boron).
 This leaves the n-type with one more proton than electron
giving the n-type a positive charge.
 And the p-type now has one more electron the proton
yielding a negative charge.
 This creates an electric field. With out this electric field the
freed electron(freed by a photon) would just return to the
same hole.
 But because of the electric field the freed electron will
move from the negative area to the positive area creating
an electric current. And the holes will move in the other
direction.
Technology Using Solar Energy
•
Types of cells:
1. Crystalline Silicon
a. Single crystal
b. Multi-crystalline
c. Ribbon
d. Film
2.
Thin films materials
a. Amorphous Silicon
b. Cadmium Telluride
c. Copper Indium Diselenide
•
3. Concentrators
Components:
1. PV
2. DC-AC Converter
3. Backup Power Generator
4. Stabilizer
5. Electrical Panel
Source:DOE/GO-10097-377 FS 231 - March 1997
SCI 322U – Energy and Society II Presentation
By Jeremy Parra and Sandrio Elim
23
Types of PV Cells
1.
2.
3.
4.
5.
Monocrystalline Silicon Cells
Multicrystalline Silicone Cells
Thick-film Silicon
Amorphous Silicon
Other thin films:
• Cadmium telluride
• Copper indium diselenide
• Gallium arsenide
• Tandem cells
1. Monocrystalline Silicon
•Most efficient PV tech
•Complicated process
•High Cost to manufacture
2. Multicrystalline Silicon
•Cheaper
•Simpler process
•Less efficiency
•Granular texture
3. Thick-film Silicon
•Continuous process
•Fine grained
•Bounded to aluminum frame
4. Amorphous Silicon
•A thin homogenous layer
•More effective in absorbing lights
•Also known as thin film PV
•Efficiency about 6%
5. Other Thin Films
a. Cadmium telluride and Copper indium diselenide
• Still in research
• Very inexpensive process
• Expected efficiency quite high
b. Gallium arsenide
• High efficiency
• Relatively temperature independent
• For special purpose only
c. Tandem cells
• Made of two different cells
• Usually from silicon and gallium arsenide
• Better use of incoming light
Manufacturing
How It Works
Math Modeling
1.
Optimal Conditions
a. Equations
b. Independent Variables
2.
Method of Data Collection
a. Software
b. Units
Source:DOE/GO-10097-377 FS 231 - March 1997
Source:DOE/GO-10097-377 FS 231 - March 1997
SCI 322U – Energy and Society II Presentation
By Jeremy Parra and Sandrio Elim
32
Bibliography
1)
2)
3)
4)
5)
6)
7)
8)
9)
http://cosmos.colorado.edu/~hairgrov/Sun's_Energy_Generation
http://www.wikipedia.org/wiki/Deuterium
http://pearl1.lanl.gov/periodic/elements/1.html
http://www.nobel.se/chemistry/laureates/2000/public.html
http://www.scolar.org.uk/html/pdf-page.html
http://sol.crest.org/renewables/re-kiosk/solar/pv/theory/index.shtml
http://www.fsec.ucf.edu/pvt/pvbasics/
http://www.ips-solar.com/basics/solarbasics.htm
http://acre.murdoch.edu.au/refiles/pv/text.html