What are Solar Panels – & How they are made?
As more & more people are getting cautious about the environment, global solar energy demand is increasing drastically.
Solar panels are used to convert solar energy into electricity & is one of the most important components of a solar power system.
In this post, I am going to share the complete manufacturing process of solar panels. It will include solar panels, their structural composition & how they are made.
So, let’s start with the most basic concept, i.e. what are solar panels?
What are Solar Panels?
A solar panel is an array of photovoltaic (PV) cells that converts the solar energy into electricity.
Here photovoltaic cell refers to a device that is made up of semiconductor material such as Silicon & is used to convert sun’s energy into electricity.
The electricity that solar panels produce is in the form of direct current (DC). That DC is then converted into AC with the help of a solar inverter.
The conversion of solar energy into electricity is possible only because of the photovoltaic effect which we have discussed in our previous post.
Structure of Solar Panel
The structure of a solar panel composed of a number of layers formed by various substances.
Below is the visual representation of a solar cell. It consists of following parts:
i) Frame: The outermost part of a solar panel is it’s frame. It is made up of Aluminium & is used to mount assembly of solar cells in a definite structure.
Along with that, it also protects the solar cells by external damage.
ii) Glass: A 3 to 4 mm thick & highly transparent sheet of glass is placed just after the encapsulant. It protects solar cells from bad weather conditions.
iii) Encapsulant: EVA (Ethylene Vinyl Acetate) is used as an encapsulant on both sides of solar cells.
It is in the form of plastic layers & used on both sides to hold the cells in proper position & also to provide proper insulation.
iv) Solar Cells: Finally at the middle of the solar panel, the solar cells are placed.
Solar cells are also known as photovoltaic cells. These are made up of semiconductors & used to convert solar energy into electricity.
v) Back Sheet (Film): Back sheet is the final-most layer of a solar panel. It is made up of polymers & plastics & is used to provide mechanical protection & insulation.
vi) Junction Box: Finally at the last, a junction box is connected to the solar panel. It is used to take current output out of the PV cells.
How Solar Cells are made?
I have already told you about the structure of solar panels. It is nothing but an array of solar cells.
Now our main goal is to know how solar panels are made.
As I have discussed earlier that solar panels are made up of semiconductor materials like silicon.
But do you know what semiconductors are?
Semiconductors are those materials whose conductivity lies between conductors & insulators
Here conductors are those materials that allow flow of current through them.
On the other hand, insulators do not allow the flow of current. e.g. Plastic is an insulator while Iron is a conductor.
So, we can say that semiconductors are materials that lie between conductors & insulators.
It means they allow the flow of current in some conditions & not in others.
At 0 Kelvin, semiconductors work as an insulator. And, when we increase the temperature their conductivity increases.
Since, Silicon is mostly used in solar panels, so I will continue my discussion by taking Silicon (Si) into consideration.
Let’s have a look at how solar cells are made out of Silicon.
PV cells are of two main types:
- Monocrystalline &
Manufacturing of Mono-crystalline Solar Cells:
Monocrystalline solar cells are made by making Silicon boules which later on converted into wafers.
Below is the step-by-step process of manufacturing of monocrystalline solar cells.
Step 1: Making of Silicon Boules
The first step in the making of these solar cells starts with Silicon rocks. These rocks are melted down in very high temperature furnaces.
During this process, some impurities (e.g Boron & Phosphorous) are added to Silicon. This is done so as to make the Silicon electrically conductive.
Then, they are given the shape of cylindrical blocks called boule or ingots. These boules look like the one shown in the below image.
Step 2: Conversion of Silicon Boules into Wafers
Next, these boules are segmented into a form of thin disk-like structures. These structures are known as wafers.
The thickness of these wafers is about 1/10th of a millimeter. The below image clearly depicts how these wafers look like.
Step 3: Wafers to Solar Cells
Last but not the least, these wafers are converted into solar cells by adding a layer of conducting material over their surface.
This layer is added so as to make paths for charge to flow out of the solar cell.
Some common metals used for making these pathways are Aluminium, Nickel, Chromium, etc.
Finally, the solar cells are formed & assembly of these solar cells constitutes solar panels.
Manufacturing of Poly-crystalline Solar Cells:
In the process of making these solar cells, the Silicon crystals are directly melted together & shattered into the solar panel itself.
Thus, it is quite easy to make polycrystalline solar panels & because of which they are lower in price.
So far, we have discussed the manufacturing process of two most popular types of solar panels.
Some other types of solar panels include thin-film PV panels, concentrated PV panels, bifacial, tiles & transparent solar panels.
We will cover all other types of solar panels in our upcoming posts.
In this post, I have tried to explain Solar panels, their structure & how they are made.
I have covered two main types of solar panels. This is so because these are the most commonly used panels.
However, in our upcoming post, we will also cover other types of solar panels.
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