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State the principle and working of photovoltaic cell used for solar energy.
2 Answers
written 3.4 years ago by |
Solar Energy:
Principle:
Silicon is abundant in supply and relatively inexpensive in production.
Conversion of solar energy directly on to electrical energy in a solar cell:
written 2.9 years ago by |
Photovoltaic Cells :
"Photovoltaic cells or Solar cells" are the semiconductor devices which coverts sunlight into direct current electricity on illumination.
The Solar cells or Photovoltaic cells are made out of semiconductors which have the capacity to absorb light. When n-type and p-type semiconductor are brought together a semiconductor diode is formed. The semiconductor diode separates and collects the carriers and conducts the generated electric current preferentially in a specific direction.
A typical silicon photovoltaic cell is composed of a thin wafer consisting of an ultra thin layer of phosphorus doped. (n-type) silicon on top of boron doped (p-type) silicon. Hence a p-n junction is formed. A metallic grid forms one of the electrical current contacts of the diode and allows light to fall on the semiconductor between the grid lines. An antireflective layer between the grid lines increases the amount of light transmitted to the semiconductor. The cell`s other electrical contacts is formed by a metallic layer on the back of the solar cell.
When light radiation falls on the p-n junction diode, electron hole pairs are generated by the absorption of the radiation. The electrons are drifted to and collected at the n-type end and the holes are drifted to p-type end. When these two ends are electrically connected through a conductor, there is a flow of current between the two ends through the external circuit. Thus photoelectric current is produced.
Importance of Photovoltaic cells :