In solar panel, solar cells are made of from silicon-based material, when the beams of sunlight strike on photovoltaic cells; the silicon-based material is called semiconductor which converts sunlight to electric energy. Actually, in a solar PV sunlight falls on a thin layer of silicon which dislocates electrons in the thin semiconductor creating a flow of electron (electric current).

 

I want to ask what is the mechanism of this process ???

 

 

Thanks a lot,

You alluded to it already. A photon excites an electron into the conduction band of the semiconductor. (It's similar to the photoelectric effect). The doping of the material means there is an electric field present, which provides the electrons for the effect and drives the electrons (and the holes) along.

 

http://inventors.about.com/library/inventors/blsolar3.htm

http://www.physics.org/article-questions.asp?id=51

Silicon (single-crystal, polycrystalline, or amorphous) is only one possible material. Other semiconductors are used, and organic dyes look very promising to replace semiconductors.

If the solar cell is put in the sun, photons will strike the surface of the Silicon and pass their energy on to electrons. A typical photon can eject one electron from its nucleus creating a free electron and a vacancy. These free electrons will feel the effect of the electric field. They are pushed towards the junction on the N-side and away from the junction on the P-side. Likewise, the vacancy, which has a net positive charge, will be pulled towards the junction on P-side and pushed away from it on the N-side. This upsets the balance of electric charge. If an external current path connects the two sides of the cell the electrons can be swept back to the P-side to reunite with their vacancies. As sun continues to hit the Silicon cell a steady flow of electrons or current is created. The power generated by the cell is the product of this current and the voltage created by the cell’s electric field.

This is the mechanism involved in production of electricity by silicon in solar cells.

Tiny update: the electron excited by the photon comes from the valence band, hence is not attached to one atom. It's broadly delocalized over many atoms. After excitation, it's in the conduction band, which isn't quite the same as free; for instance it mass differs from an elelctron in vacuum.

Tiny update: the electron excited by the photon comes from the valence band, hence is not attached to one atom. It's broadly delocalized over many atoms. After excitation, it's in the conduction band, which isn't quite the same as free; for instance it mass differs from an elelctron in vacuum.

Right!