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Photovoltaic Effect

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Photovoltaic Effect Definition

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Many of us have been using solar panels in our homes for quite some time and are saving a huge amount of money on our electricity bills. But how does a solar panel work, and how does it create electricity which powers our homes? Well, here we have explained the working of a solar panel that works on the principle of the photovoltaic effect. The photovoltaic effect, or in short, PV effect, is the process that enables a solar panel to generate voltage or electric current. 

The solar panels you see in solar power plants are made by photovoltaic cells and exposed to the sunlight. It is the effect that makes the photoelectric effect of solar panels are useful and allows them to generate electricity in the first place. The photovoltaic effect in solar cells was first discovered in 1839 by Edmond Becquerel when he experimented with wet cells. 


Explain Photovoltaic Effect

The photoelectric effect of solar panels happens due to the presence of two different types of semiconductors. These semiconductors are p-type and n-type. These two are joined together to form a p-n junction. By making these two junctions come together, an electric field is formed in the junction region, and electrons start to move to the positive side, and holes that are present in the cell start to move to the negative side, which is the n-side. The electric field causes the charged particles to move in one direction and positively charged particles to move in the other direction.

Now you might not know, but the light is coming from the sun, and all the other forms of light are composed of photons, which are also known as the small bundles of electromagnetic radiation energy. These photons, when they hit the surface of the photovoltaic cell, get absorbed, and their energy is transferred to the cells present in the cells. Precisely the energy of the photons goes to the electrons which are present in the material. As a result, the electrons get excited, and they start jumping to the higher energy state, which is known as the conduction band. 

Once the electrons are jumping to the conduction band, they leave behind holes in the valence band. This movement of the electron creates energy and makes two charge carriers along with an electron-hole pair. All in all, the motion of the electrons when they move in the excited state causes energy formation which also leads to a photoelectric effect in solar panels, which then converts into electricity by the solar cell. This was the principle of the photovoltaic effect on solar panels and solar cells. 


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(Solar panel in solar power plant.)


Soiling Effect on PV Modules

When there is soiling, you are going to face a power loss, that's for sure. The Pv modules' power output depends on their amount of irradiance, which catches the solar cells. Several factors come into play that define the optimal output of the PV module. However, the PV module environment is one of the leading parameters that define the optimal output of the solar cell. A soling effect is the loss of a generation of electricity due to snow, dirt, dust, and other particles that stuck at the PV module's surface, making it hard for the protons of the sunlight to hit the surface and transfer their energy. Even dust that forms on the solar cell with time leads to the soling effect, and it depletes the overall energy generation of the panel. 


Conclusion 

That's how a solar cell works, and that's how with the use of the photovoltaic effect, it can generate clean electricity for us to use. The future of energy generation depends on how we use solar panels and how much efficiency we can make them. As our sun will last for more than 1 billion years from now on and being able to create electricity from it is surely a blessing that we need to take advantage of. 

FAQ (Frequently Asked Questions)

1. What Would Be the Effect of Temperature on Solar Cell Performance?

Answer. Like all the devices which are said to be semiconductors, a solar cell is also sensitive to temperature. The increase in temperature will show the reduction in the bandgap of a semiconductor. Thus it will affect most of the semiconductor properties. On the other hand, the decrease in the bandgap of a semiconductor will cause an increase in temperature. In solar cells, the parameter which is most affected by the temperature is the open-circuit voltage. Thus, the effect of temperature on solar cell voltage is inversely proportional, and with an increase in temperature, the voltage will go down.  


The open-circuit voltage decreases with the increase in temperature because of its nature of inversely proportional temperature dependency. As a result, when the temperature of the solar cell is hot, its efficiency will decrease, and when it is below 25 degrees celsius, its power generation efficiency will be optimal.

2. Do Electrons Need an External Circuit to Maintain the Power Flow Consistency in the Solar Panel?

Answer. Well, the basic idea of the photovoltaic effect works on the principle of photons and electrons. The photons can excite an electron and make them jump from a valence bond to the conduction band. This type of jumping off an electron occurs in all the materials, so it's not just a p-n junction occurrence. In most cases, the electron and the hole created in the valence band remain near each other. Thus, the electron drops back down. However, it is possible to make scenarios where electrons and the hole don't come together and take different paths.


Well, there is nothing special, and the external circuit is not required for the consistent flow because once the depletion zone is built enough of the voltage, then you are no longer going to see electrons or holes enlarging the depletion zone. After some point, the electric fields will help the solar cell to maintain its power flow.