How do Solar Panels Work?
Sun is the ultimate source of energy on the earth. All the energy that we use today is somehow part of the sun’s energy.
Even the energy in fossil fuels came from the sun which is captured through photosynthesis.
But, fossil fuels are limited. And, solar energy is one of the best renewable sources of energy.
In this post, I am going to share a key guide on how solar panels convert sunlight into electricity.
Before I begin, let me share a bit about the p-type & n-type semiconductors.
p-type & n-type Semiconductors
A solar panel is a combination of smaller solar cells over a metal framework.
These solar cells are made up of semiconductors doped with some impurity elements for electrical conductivity.
Silicon (Si) is a commonly used one, so I will explain everything by taking it into consideration.
The structure of Si consists of four electrons in the external shell.
When an impurity element having 5 electrons in the outermost shell (e.g. Phosphorus) is added to Si, it gives rise to n-type semiconductor.
During this process, an extra electron remains in it which is responsible for electrical conductivity.
In the formation of p-type semiconductors, we add impurities having 3 electrons (e.g. Boron) in the outermost shell.
When Boron (B) is added to Si, a hole is produced due to lack of electrons in Boron. This hole is positively charged.
In this way, the combination of Si & B form p-type semiconductors.
Till now, we have seen that n-type consists of free electrons & p-type have a positively charged hole.
Now, let’s have a look at the internal composition of solar cells.
Internal Composition of a Solar Cell
In the making of solar cells, Si boules are sliced into thin disks called wafers.
These wafers consist of two layers. The uppermost layer is doped with Phosphorus to form n-type semiconductor.
And, the lowest layer is doped with the Boron to form a p-type semiconductor.
These two layers when came in contact with each other forms a p-n junction.
The electrons at the boundary of the n-type layer get diffused with the holes near the boundary of the p-type layer.
Thus, a layer is formed in between both layers due to diffusion. This layer is electrically neutral & called the depletion layer.
The below image clearly depicts how the formation of the depletion layer.
Note: In Si wafers, the n-type layer is made thin compared to p-type. This layer is made thin so that sunlight (photons) can enter the depletion layer.
How do Solar Panels work?
Till now, we have seen how depletion layers are formed in Si wafers. These wafers are converted into solar cells after adding metal strips over the surface.
Let’s have a look at what happens when sunlight falls over these solar cells.
When photons fall on the surface of solar cells, they pass the n layer & are absorbed in the depletion layer.
In the depletion layer, these photons excite the electrons present in the outermost shell of Si.
These negatively charged electrons are collected by the metal strip over the surface of the n-layer. As a result, a negative potential is developed at the terminal attached to the n-type layer.
While the positively charged holes develop positive potential at the terminal attached to the p-type layer.
You can have a look at the below image for better understanding.
When an electrical device is attached to these terminals, the flow of electric current takes place.
This is how electricity is produced by the help of solar cells.
What are semiconductors?
These are those materials having conductivity between conductors & insulators. e.g. Silicon, Ge, etc.
What are solar panels made of?
The solar panels are made up of materials like Silicon doped with impurities for electrical conductivity.
What happens when sunlight falls on solar cells?
When sunlight falls on the surface of solar cells, the photovoltaic effect takes place & sunlight gets converted into electricity.
Do Solar panels work at night?
No. It is so because solar panels convert sunlight into electricity. So, it is impossible for them to generate electricity without sunlight at night.
Solar power is one of the best renewable energy sources on the earth. We use solar panels to convert this energy into electricity.
In this post, I have tried my best to explain how solar panels work. Along with that, I have also discussed the internal composition of solar cells.
I hope this post is helpful for you to understand the basic working of solar panels.
If still any query left then you are always welcomed to leave a comment below this post.
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