14-06-2013, 01:06 PM
The impact of nanoscale science on solar energy production
nanoscale science.ppt (Size: 1.78 MB / Downloads: 52)
What is Solar Energy?
Energy produced by the sun
Clean, renewable source of energy
Harnessed by solar collection methods such as solar cells
Converted into usable energy such as electricity
Energy from the Sun is Abundant
Solar power systems installed in the areas defined by the dark disks could meet the world's current total energy demand
Current U.S. Energy Demand
The US consumes ~25% of the world’s energy, but has only 4.5% of its population
Solar cells would need to cover an area comparable to the size of Texas to meet US energy demand today
Photovoltaic Solar Cells
Generate electricity directly from sunlight
2 Main types:
Single-crystal silicon (traditional)
Widespread
Expensive to manufacture
Dye-sensitized (“nano”)
Newer, less proven
Inexpensive to manufacture
Flexible
A Closer Look at Solar Cells
How do traditional, silicon-based solar cells and newer, dye-sensitized solar cells work?
What are the advantages and disadvantages of each type of cell?
How a Silicon-Based Solar Cell Works
Light with energy greater than the band gap energy of Si is absorbed
Energy is given to an electron in the crystal lattice
The energy excites the electron; it is free to move
A positive “hole” is left in the electron’s place
This separation of electrons and holes creates a voltage and a current