Solar Cells: Energy for the Future

1
Solar Cells Energy for the Future

• By Eamon Penney
• And
• Adam Growald

2
The Sun

• The sun is the most abundant energy source known
  on Earth
• Nuclear fusion reactions account for the Energy
  the sun generates 3.86e33 ergs/second or 386
  billion billion megawatts)
• 1,000 watts of energy per square meter
• Some energy travels to Earth, solar cells are an
  attempt to capture some of that energy.
• Energy a result of nuclear fusion
• Solar Energy is safe, free, and with no
• byproducts
• In three days the amount of energy that
• reaches the Earth more then equals that of
  all
• fossil fuels believed to be on the Earth

3
Solar Cells The Basics

• Semiconductor
• Electron Field

4
Silicon as a Semiconductor

• Crystalline Structure (4 atoms in outer shell)
• Impure Silicon
• Free carriers
• Phosphorous impurities (5 outer atoms)
• N-type silicon Vs. P-type silicon Doping
• Diode electrical barrier

5
Solar Cell in Practice

• Free Electrons want to equilibrate but cannot
  pass diode, thus they go through the conductor.

6
Solar Cell Specifics

• Solar Cells only absorb around 15 of sunlight,
  why so little?
• Band gap energy
• High energy wavelength vs. low energy wavelength
• Bottom can be covered by conducting metal, but
  top cannot. (series resistance)
• Grid

7
Solar Cells in Practice
8
Making Solar Cells More Effective

• Higher Energy Band Gap above, lower below
• Multi Junction Cells
• Weather
• Batteries (high maintenance)
• Utility Grid

Obstacles
9
History Of Solar Cells

• First used during Industrial Revolution
• Henri Becquerel discovered the photovoltaic
  effect
• Considered inefficient for many years
• With upcoming in semiconductor technology more
  research gone in.
• First put into practical use by NASA and now
  applied many places

10
Bibliography

• Aldous, Scott. How Solar Cells Work.
  Howstuffworks.com. 25 May 2004lthttp//science.how
  stuffworks.com/solar-cell.htmgt.
• History of Solar Power. Go Solar Company. 25 May
  2004lthttp//www.solarexpert.com/pvbasics2.htmlgt.
• Sun. Views fo the Solar System. 25 May
  2004lthttp//www.solarviews.com/eng/sun.htmgt.