This document provides an overview of photovoltaics and solar energy. It discusses the history of photovoltaics from 1839 when the photovoltaic effect was discovered to recent developments. It describes the difference between the photovoltaic effect and photoelectric effect. It also explains how semiconductors are produced through doping to create P-N junctions and the different types of solar cells including thin film, polycrystalline and monocrystalline cells. The document concludes with a look at future developments in solar energy technology.

1. Project
BY:

2. Overview
History of Photovoltaics
Photovoltaic effect vs. Photoelectric effect
Semiconductor production
P-N junction
Different types of PV cells and the efficiencies
A brief look at the future of solar energy

3. What is Solar Energy
and How is it used?
Radiation from sun
• Earth receives ~174 petawatts (1015 watts) at the
upper atmosphere. Only ~ 47% is absorbed.
• Solar panels
Photosynthesis

4. History of Photovoltaics
French scientist Edmond Becquerel discovers the
1839
photovoltaic effect
The first solid state photovoltaic cell was built by
1883
Charles Fritts
Albert Einstein published his paper on the
1905
photoelectric effect
The first practical photovoltaic was developed at Bell
1954
Laboratories
1970’s Solar energy became commercialized
World record efficiency reached 44% with a
2012
multijunction cell

5. Photovoltaic Effect vs.
Photoelectric Effect
Photovoltaic Effect Photoelectric Effect
• The creation of voltage or electrical • The emission of electrons from a solid,
current in a material upon exposure to liquid, or gas upon exposure to light.
light.
• Electrons are ejected when excess
• Electrons absorb energy and become energy is absorbed.
excited.
• If the photon energy is too low the
• Electrons move to the conduction electrons will not be able to escape
band to become free.

6. Doping
• A process first developed by John Robert
Woodyard
• Doping intentionally introduces impurities into a
pure semiconductor for the purpose of
modulating its electrical properties
• Group IV semiconductors such as Silicon are
used
• By doping semiconductors the we are able to
form P-type and N-type semiconductors

7. P-type Semiconductor
• Doped with Group III
element such as Boron
• Abundance of holes or
electron deficiencies
• Electrical conduction due
primarily movement of
holes

8. N-type
Semiconductor
• Doped with Group V
elements such as
Phosphorous
• Abundance of extra
electrons
• Electrical conduction due
primarily to movement of
electrons

9. P-N Junction

10. Thin-film Solar Cells
•
Around 8% efficiency
•
Very thin layers of
photovoltaic material.
The thickness is
anywhere between a
few nanometers to tens
of micrometers
•
Small portion of the solar
cell market

11. Polycrstalline Solar Cells
•
Around 14-16 %
efficiency
•
Uses multiple crystal to
harness the suns light.
•
Generally, these are
cheaper and easier to
install.

12. Monocrystalline Solar
Cells
•
Around 16-19 %
efficiency
•
Made from a single
crystal cell
•
Generally, these are the
most popular and most
efficient cells on the
market.

13. Multijunction Cells
• Efficiencies up to 44 %
• Not available on the market. Only used experimentally in a lab
setting.
• Cells are used in tandem to gain better efficiencies

14. Solar Cell Efficiencies

15. Solar Cell Diagram
• Each cell produces 0.5 Volts
• Cells are connected in series
of 18 Volts, which
creates a module of 36 cells
• A photovoltaic system needs
an array of cells, charge
controller, battery system, an
inverter, and wires to connect
the system

16. Future for Solar Energy
•
Over the last 20 years, prices have
dropped significantly
•
Clean renewable energy
•
Production has increase
exponentially
• Dye-sensitized solar cell (DCS)
technology
• Many other examples

17. References
“Brown, Eric W. "An Introduction to Solar Energy." N.p., n.d. Web. 6 Apr. 2013.
Future Energy.” – Concepts for Future Electricity Generation. Web. 12 Apr. 2013.
Honsburg, Christiana, and Stuart Bowden. "The Photovoltaic Effect." PVEducation. N.p., n.d. Web.
11 Apr. 2013.
“How Does Solar Power Work?” Solar Power. Web. 2 Apr. 2013
Marti, Antonio, and A. Luque. "Thermodynamics of Solar Energy Conversion.” Next Generation
Photovoltaics: High Efficiency through Full Spectrum Utilization. Bristol: Institute of
Physics, 2004. SciFinder. Web. 19 Mar. 2013.
Miessler, Gary L., and Donald A. Tarr. “The Crystalline Solid State.” Inorganic Chemistry. 4th ed.
Upper Saddle River, NJ: Pearson Prentice Hall, 2011. 238-239. Print.
Moore, Taylor; "Opening the Door for Utility Photovoltaics", EPRI Journal, Jan./Feb. 1987; Palo Alto,
CA; 1987
"Solar Cell Efficiency." NREL. National Renewable Energy Laboratory, n.d. Web. 02 Apr. 2013.
"Types of Solar Panels." Sun Connect. N.p., n.d. Web. 05 Apr. 2013.
Zyga, Lisa. “Solar Thermal Process Produces Cement with No Carbon Dioxide Emissions.” Science
News, Technology, Physics, Nanotechnology, Space Science, Earth Science, Medicine.
Phys.Org, 10 Apr. 2012. Web. 2 Apr. 2013
.