Pros and Cons of Solar cell

Pros:

1. Solar energy is a renewable resource.
2. Except for the processes involved in manufacturing the materials, transportation of the goods, and installation solar energy does not give off any harmful substances.
3. Sun, unlike fossil fuels, does not exist only in specific pockets of the earth: it is everywhere, although not in evenly distributed concentrations.
4. Sunlight is free. Although the initial investment of solar cells may be high, once installed, they provide a free source of electricity, which will pay off over the coming years.
5. The production of energy from the use of fossil and some renewable fuels (e.g. wind turbines) can be noisy, yet solar energy produces electricity very quietly.

Cons:
1. The initial costs for components can be high. Currently, prices of highly efficient solar cells can be above $1000, and some households may need more than one. This makes the initial installation of solar panels very costly.
2. Rarely efficient enough, predictable enough, or powerful enough to provide a substantial portion of a specific user’s needs.
3. Not every location is a feasible site for solar.
4. Solar energy is only able to produce electricity during daylight hours, which means for around half of each day, solar panels are not producing energy. The weather can also affect the efficiency of solar cells.

C. Bruce Lowery .(2007). NOT SO FREE ENERGY FROM THE SUN. Energy Consumer Egde.
[online] URL: http://www.energy-consumers-edge.com/pros_and_cons_of_solar_power.html
(01/07/08)

Janice

Theories behind solar cell

Theory

1.) The light energy will be absorbed by semi-conducting materials like silicon when photons in sunlight hit the solar panel.

2.) Negative-charged electrons are knocked loose from atoms and are able to flow through the material to produce electricity while the positive-charged holes flow in opposite direction.
When a photon hits a piece of silicon, the photon can pass straight through the silicon — this (generally) happens for lower energy photons, reflect off the surface, and it could also be absorbed by the silicon, if the photon energy is higher than the silicon band gap value. This generates an electron-hole pair and sometimes heat, depending on the band structure. Hence current electricity will be created.

3.) The two main modes for charge carrier separation in a solar cell are namely drift of carriers, which is driven by an electrostatic field established across the device, and the diffusion of carriers from zones of high carrier concentration to zones of low carrier concentration.
In the p-n junction solar cells, the dominant mode of charge carrier separation is by drift. However, in non-p-n-junction solar cells (typical of the third generation of solar cell research such as dye and polymer thin-film solar cells), a general electrostatic field has been confirmed to be absent, and the dominant mode of separation is via charge carrier diffusion.

Wikipedia. (2007). Solar Cell. Wikipedia: The free encyclopedia. [on-line]

URL: http://en.wikipedia.org/wiki/Solar_cell (01/07/08)

Qinyan