Photovoltaic Solar Power


The Photovoltaic Solar Power is the electricity generated by employing solar cells. A typical Solar Cell directly converts incident sunlight on the cell into solar electricity.


The Photovoltaic Effect

A.E. Becquerel
A. E. Becquerel

The photovoltaic effect was discovered by French Physicist – Alexandre Edmond Becquerel (A.E.Becquerel). This discovery was made by A.E.Becquerel in 1839, when he was experimenting with an electrolytic cell made up of two metallic electrodes.

He observed that certain materials would produce small amount of electric current whenever they were exposed to sunlight. Thus Photovoltaic technology was born. The Solar Cells and Solar Panels work on this principle.

This effect allows direct conversion of sun’s light energy into Electricity. The Electricity is obtained by the generation & transportation of positive and negative charges inside the semiconductor after interaction with light.

After this you would say, “This indeed was a superb discovery, but why are we using semiconductors?”


Why Semiconductors?

This would have been your obvious question. The matter around us is in three different forms – Solids, Liquids (Fluids) & Gases. Each of them has different sets of characteristics. Here we will touch upon the characteristics of Solid Matter. The Solid Matter can be classified as Conductors, Semiconductors and Insulators. Lets’ take a look at each of them.

  • Conductors are materials in which the electrons in the outermost orbits are loosely held which imparts them the property of conducting electricity. It is known as Conductivity.

  • Semiconductors are materials which exhibit the properties of insulators but if exposed to heat or light they act as conductors.

  • Insulators are substances have electrons strongly held in their outermost orbits. Hence these electrons aren’t mobile and they resist the flow of electricity.

Semiconductors are needed for generating photovoltaic solar power. But just heat or light isn’t enough for a semiconductor to start generating electricity. The light will free the electrons, but electricity will be produced only after they start flowing.


Creation of Charges

Most common semiconductors known to you are silicon and germanium.

This semiconductor is then doped with either a donor or accepter impurity. Doping modifies the electrical properties of the semiconductor by increasing the number of free charge carriers.

P-Type doping creates an abundance of positive charges (holes) in the semiconductor hence reducing the number of electrons.

N-Type doping creates large number of negative charges (electrons) in the semiconductor thus increasing the number of electrons.

Now that we have both the P-Type and N-Type semiconductors.

Then we need a circuit. The circuit is said to be a closed path provided for electrons to flow. The circuit is constructed using conductors like copper or aluminum wires.


Working

When the P-Type and N-Type doped silicon are brought together the excess electrons from the N-Type silicon diffuse with P-Type silicon. Thus the initially N- Type silicon becomes positively charged and vice versa. An electric field is set which tends to force the electrons back into the N region and the holes back into the P region by this a PN-Junction is set up.

Now when the junction is illuminated, photons (packets of solar energy) transfer their energy to electrons. These electrons then get transferred from valence band to conduction band within the material resulting in a buildup of voltage between the two electrodes.

When we have this P-N Junction Semiconductor then we will make an interconnection between the P-Type and the N-Type. The current will flow from the N-Type layer to the P-Type layer.

As we have voltage and current in our solar cell, we have generated photovoltaic solar power. The Product of Voltage and Current is termed as Power and is measured in Watts. If we connect an electrical load, it will perform work from the electricity generated.


Indeed the photovoltaic solar power has been a boon to all of us in these trobled times of energy scarcity. You will hopefully have greater insights about how you can take advantage of this power



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