Tuesday, 3 December 2013

About Solar Cell

How Solar Cell Works ?

Solar cells are the one which converts sunlight into electricity,Silicon is a semiconductor material, that has some of the properties of metals and insulator and we will see how this cells convert sun rays into electricity,

Sunlight is composed of pockets of energies called photons, which are radiates from the sun. These photons hits the silicon atoms and transfer its energy to loose an electron from the atom,One photon of energy can eject one electron from the atom of silicon,you can compare this with the white ball in a game of pool,which transfer its energy to the colored ball if its strikes.

solar cell

Creating an electron from the atom of silicon is one of the part and the next part is flow of electron,that needs an electrical imbalance.The internal organisation of the silicon makes it possible,The silicon atoms are tightly bounded by bond structure,There is a technique called doping,which means making silicon spare or missing of electrons,thus we can create two types of silicon,N-Type and P-Type.
Working Princible of PV Cells

As this two types are placed side by side then the electrons which are spare from N-Type silicon jumps to the P-type silicon to fill the gap of missing electrons.When an electron is missing from an atom,a hole is created,HOLE is positively charged,When photon eject an electron from the silicon atom then a hole will be formed at that place.

The circuit was completed by connecting a load which may be a Light,Fan etc...,Once the circuit was complete then electron starts to flow otherwise it won't be created.

What is a Photovoltaic Cell?

The photovoltaic cell is made up of semiconductor material,as the photon of certain frequency hits an electron,the electron absorbs and ejects out from the atom of semiconductor and an external circuit was connected from the (+) and (-) poles thus electrons flows between them.

PV Cell Basic Schema
SiO2: It is the basic element of semiconductor segments. This chemical is used in the making of the transistors and diodes that are used in electronic circuits.
Silicon Wafer: The silicon wafer is responsible for creating a semiconductor environment. The process of separation to the poles occurs with SiO2.
Flow of Electrons: The extra electrons that come out as a result of the photons move from (-) pole to (+) pole and generate electricity.

Working Principle of Photovoltaic Cells.

Figure 1 shows a PV cell in a normal condition without sunlight.As it shows no movement of electron or holes so no current will be generated.
PV Cell without Sun Light
Figure - 1

PV Cell with Sun Light
Figure 2 shows a PV cell which is active,The sunlight falls on the atom of a semiconductror thus increase the number of electrons and resulted in increasing voltage.As long as sunlight falls on the cell,this electron generation will occur.

Note: A silicon surface of a cell does not completely transform the power of the light which falls on it into electricity. The main reason for this is that even though there are many colors in light only the red color is transformed into electricity.Certain frequency of the sunlight was converted into electricity and others are not,The electrons accepts certain frequency and absorbs energy and other are wasted as a heat,or not absorbed.