Structure of a Photovoltaic Cell

Structure of a Photovoltaic Cell

Two individual pieces of silicon happen to be electrically neutral. But when two impure silicon pieces -– the P-type and N-type -– are brought in contact with each other, an electric field is formed. The free electrons present on the N side seeing all the holes on the P side rush to fill them fast. All free electrons are unable to fill the free openings. The entire arrangement would, in fact, be wasted if they had. But, exactly at the opening point, they mix successfully to form a kind of barrier which makes it increasingly tough for electrons located on the N side to make the move to side P. Gradually, the process reaches a point of equilibrium and there exists an electric field dividing the different sides. This field serves as a kind of diode, permitting and even forcing electrons to drift from the P to the N half, instead of the other way round.

 

 

When light in proton form hits the solar cell, the energy results in dividing the hole-electron couples. Each photon carrying sufficient amount of energy will usually be able to free just a single electron, leading to a free opening as well. If this occurs very close to the field of electricity, or if free opening and free electrons tend to flow into influence range, the field is likely to shift the electron to side N and the hole to side P. This results in even more disruption of neutrality of electricity, and if an external charged path is presented, electrons make use of the path to travel to the P side to combine with openings sent by the electric field, carrying on work in the process. The flow of electron results in the current and the electric field of the cell results in the formation of a voltage. Power is formed as a product of both voltage and current.

 

A few elements remain before the cell can be used. Silicon is a highly shiny substance that can push photons away prior to the completion of their job. In order to remedy this, it is normal to apply an anti-reflective coating which lessens the losses. The ultimate step is the installation of a cover plate made of glass or any other object that can offer protection to the cell from the elements. The amount of energy absorbed from sunlight by the solar cell is not very much.