October 11,2013

ECEN 2060

Lecture 21

Fall 2013

Homework Problems\Chapter 5 problems

Solar Spectrum

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Power Spectrum Planck’s Law Total energy Radiated Stefan-BoltzmannLaw

Suns Spectrum for T= 5800

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

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Requirement for creating an electron hole Pair is hν> Eg

h

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

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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.

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

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For A=100 2cm 2/40 cmmaI sc 212 /10 cmAIo

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

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Contact resistance, resistance in diode outside of the junction region

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

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1 Voltages for cells add in series2 Currents for each cell add in parallel

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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