When energy is added to pure silicon it can cause few electrons to break free of their bonds and leave their atoms. These are called free carriers, which move randomly around the crystalline lattice looking for holes to fall into and carrying an electrical current.
However, they are very few and are not very useful. As a result, we have a lot more free carriers than we would have in pure silicon to become N-type silicon. The other part of a solar cell is doped with the element boron with 3 electrons in its outer shell to become P-type silicon.
Now, when this two type of silicon interact, an electric field forms at the junction which prevents more electrons to move to P-side. When photon hits solar cell, its solar energy breaks apart electron-hole pairs. Each photon with enough energy will normally free exactly one electron , resulting in a free hole as well. If this happens close enough to the electric field, this causes disruption of electrical neutrality, and if we provide an external current path, electrons will flow through the P side to unite with holes that the electric field sent there, doing work for us along the way.
This electron flow provides the current. As we know that photon is a flux of light particles and photovoltaic energy conversion relies on the number of photons striking the earth.
On a clear day, about 4. Only some of these photons that are having energy in excess of the band gap are convertible to electricity by the solar cell. When such photon enters the semiconductor, it may be absorbed and promote an electron from the valence band to the conduction band, that creates a hole in the valence band. After that the electron in the conduction band and hole in valence band combine together and forms electron-hole pairs.
Thus when we connect these p and n layers to external circuit, electrons flow from n-layer to p-layer, hence current is generated.
The electrons that leave the solar cell as current give up their energy to whatever is connected to the solar cell, and then re-enter the solar cell. Once back in the solar cell, the process begins again to produce more solar energy. The Mono crystalline silicon cell is produced from pure silicon single crystal.
Since the Mono crystalline silicon is pure and defect free, the efficiency of cell is higher. Polycrystalline solar cells use liquid silicon as raw material.
Since the polycrystalline silicon involves solidification process the materials contain various crystalline sizes. Hence, the efficiency of this type of cell is less than Mono crystalline solar cell. Amorphous silicon cells are developed by depositing silicon film on the substrate like glass plate. Technology wise there are three types of solar cell technology:. The solar panel or solar array is the interconnection of number of solar module to get efficient power.
There are many practical applications for the use of solar panels or photovoltaic. It is first used in agriculture as a power source for irrigation. In health care, solar panels can be used to refrigerate medical supplies. PV modules are utilized in photovoltaic systems and include a large type of electric devices:. If you like this article please share it with your friends. Enter your email address.
Sign Up. Saif M. He completed his engineering studies in and is currently working in a large firm as Mechanical Engineer. He is also an author and editor at www. Notify me of follow-up comments by email. Notify me of new posts by email. This site uses Akismet to reduce spam. Learn how your comment data is processed. Solar Cell and Types Contents show. Solar Cell and Types 1.
Types of Solar Cells. Working of Solar Cell. Applications of Solar Cells.
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