1. A Review of Photovoltaic Cells David Toub ECE423 12/16/06

2. Agenda Introduction Functionality Semiconductor Properties VTC Efficiency and PV Design Auxiliary Design Applications Research Conclusions

3. 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

4. Functionality pn diode No illumination –Diode behavior –e, h separated Illumination –Incident photons create e-h pairs –E field  e-h pairs separate Photovoltaics.” Wikipeda, The Free Encyclopedia. Downloaded from www.wikipedia.org on 12/02/06.

5. 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

6. VTC Performance Limits P m = V max x I max Incorporate load Ventre, Gerard. Messenger, Roger A. Ventre, Jerry. Photovoltaic Systems Engineering. CRC Press Technology and Industrial. 2004

7. Energy Conversion Efficiency η =Pm/(E x Ac) Primary Challenge Incident photons –E p <E bg  E lost –E p >E bg  E e - + E lost –E p =E bg  E e - Silicon tradeoff –High bg  loss –Low bg  E, V reduced –Optimal at bg=1.4eV

8. Loss Tradeoffs Cell Top –Must be transparent –Too thin  bad conduction Cell Interior grid –Large grid helps e - ’s –Large grid blocks photons

9. Auxiliary Design Heavy modules –structural stress –Wind tension Pollution Fan Example –Speed –Acceleration –Without illumination E/V  Ah

10. Applications 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

11. Research Thin Film –Cheap –Increased unit loss –Multilayer  Efficiency Nanocrystalline –Thin film + mesoporous MO –Increased internal reflection –Great efficiency  expensive

12. Conclusions Environmentally benign Inefficient  uncommon  Still fuel Future  Efficiency increasing  Cheaper

13. References 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 “Two layer organic Photovoltaic Cell.” -- Volume 48, Issue 2, pp. 183-185 Research Laboratories, Eastman Kodak Company, Rochester, New York. Applied Physics Letters -- January 13, 1986 Harmon, C. “Experience Curves of Photovoltaic Technology.” IIASA Publications. 2000. “Photovoltaics.” Wikipeda, The Free Encyclopedia. Downloaded from www.wikipedia.org on 12/02/06. Green, M. A. Solar cells: Operating principles, technology, and system applications. Englewood Cliffs, NJ, Prentice-Hall, Inc., 1982. 288 p. Wohlre, Dieter. Meissner, Dieter. “Organic Solar Cells.” Advanced Materials. Volume 3, Issue 3, Pages 129 – 138. Verlag GmbH & Co. KGaA, 1991. American Journal of Physics -- Volume 61, Issue 3, pp. 286-287 American Association of Physics Teachers. March 1993 O’Regan, B. & Grätzel, M. A low-cost, high efficiency solar cell based on dye-sensitized colloidal TiO2 films. Nature 353, 737–740 (1991). McCann,MichelleJ. Catchpole,KylieR. Weber, Klaus J. A review of thin film crystalline silicon for solar cell applications. Part 1 : native substrates. 2001 Shah, A. Torres, P., Tscharner, R. Photovoltaic technology: the case for thin-film solar cells. Institute of Microtechnology (IMT), University of Neuchatel, Rue A. -L. Breguet 2, CH-2000 Neuchatel, Switzerland. University of Applied Science, Avenue de l'Hotel-de-Ville 7, CH-2400 Le Locle, Switzerland