October 11,2013
ECEN 2060
Lecture 21
Fall 2013
Homework Problems\
Chapter 5 problems
Solar Spectrum
Power Spectrum Planck’s Law
Total energy Radiated Stefan-Boltzmann
Law
Suns Spectrum for T= 5800
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Cost of Solar Cells
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Types and Efficiencies of Some Solar Cells
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The Useable Solar Spectrum
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Two dimensional view
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Energy Level Diagram
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Photon Activation
Requirement for creating an electron hole
Pair is hν> Eg
h
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Holes or the Absence of an Electron in the
Conduction Band
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Start Lecture 22
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Cut-off Wavelengths
The issue is that you can not use the long wavelength solar energy
and the short wavelengths lose the energy above the band-gap to heat.
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Solar Spectrum
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P-N Junctions
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P-N Junction Diodes.
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P-N Junction Diode
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P-N Junction Diode.
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Equivalent Circuits
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Inverted Diode Curve
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Example
For A=100 cm
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I sc  40ma / cm 2
I o  10 12 A / cm 2
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Equivalent Circuit For Shading
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A more complete Equivalent Circuit
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Effect of
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Series Resistance
Contact resistance, resistance in diode outside of the junction region
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Series Resistance Added in
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Equivalent Circuit
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Total Equivalent Circuit.
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Combinations to Get to Useful Size
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Examples
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Modules to Arrays
1 Voltages for cells add in series
2 Currents for each cell add in parallel
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Currents add in Parallel
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Two by Three Arrays
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Output Power
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Maximum Power
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Examples Under Standard Test Conditions
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Effects of Changes in Temperature
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Shading
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Impact of Shading
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Effects of Shading
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Bypass Diode Reduces Voltage Across
Shaded Cell
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