A Review of Photovoltaic Cells
David Toub
ECE423
12/16/06
Agenda
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Introduction
Functionality
Semiconductor Properties
VTC
Efficiency and PV Design
Auxiliary Design
Applications
Research
Conclusions
Introduction
• Clean Energy
• PV System
– Cells
– Energy storage
– Charge Controller
– AC/DC converter
•Ventre, Gerard. Messenger, Roger A. Ventre, Jerry. Photovoltaic Systems Engineering. CRC Press Technology and Industrial. 2004
Functionality
• pn diode
• No illumination
– Diode behavior
– e, h separated
• Illumination
•Photovoltaics.” Wikipeda, The Free Encyclopedia. Downloaded from
www.wikipedia.org on 12/02/06.
– Incident photons create e-h pairs
– E fielde-h pairs separate
Semiconductor
• Absolute 0  Perfect insulator
• Temp increases  conduction increases
• External energy raises temperature
•Ventre, Gerard. Messenger, Roger A. Ventre, Jerry. Photovoltaic Systems Engineering. CRC Press Technology and Industrial. 2004
VTC
• Performance Limits
• Pm = Vmax x Imax
• Incorporate load
•Ventre, Gerard. Messenger, Roger A. Ventre, Jerry. Photovoltaic Systems Engineering. CRC Press Technology and Industrial. 2004
Energy Conversion Efficiency
• η =Pm/(E x Ac)
• Primary Challenge
• Incident photons
– Ep<Ebg  Elost
– Ep>Ebg  Ee- + Elost
– Ep=Ebg  Ee-
• Silicon tradeoff
– High bg  loss
– Low bg  E, V reduced
– Optimal at bg=1.4eV
Loss Tradeoffs
• Cell Top
– Must be transparent
– Too thin  bad conduction
• Cell Interior grid
– Large grid helps e-’s
– Large grid blocks photons
Auxiliary Design
• Heavy modules
– structural stress
– Wind tension
• Pollution
• Fan Example
– Speed
– Acceleration
– Without illumination
• E/V Ah
Applications
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Electric grid extensions not offered
Clean
Solar powered house
Water pumping systems
Garden lights
Automobiles
Source utility grid
Satellites, shuttles
•Ventre, Gerard. Messenger, Roger A. Ventre, Jerry. Photovoltaic Systems
Engineering. CRC Press Technology and Industrial. 2004
Research
• Thin Film
– Cheap
– Increased unit loss
– Multilayer Efficiency
• Nanocrystalline
– Thin film + mesoporous MO
– Increased internal reflection
– Great efficiency  expensive
Conclusions
• Environmentally benign
• Inefficient  uncommon  Still fuel
• Future  Efficiency increasing Cheaper
References
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Ventre, Gerard. Messenger, Roger A. Ventre, Jerry. Photovoltaic Systems Engineering. CRC Press
Technology and Industrial. 2004
F Lasnier. Photovoltaic Engineering Handbook TG Ang - 1990 - A. Hilger New York
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Harmon, C. “Experience Curves of Photovoltaic Technology.” IIASA Publications. 2000.
“Photovoltaics.” Wikipeda, The Free Encyclopedia. Downloaded from www.wikipedia.org on
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Green, M. A. Solar cells: Operating principles, technology, and system applications. Englewood
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