A photovoltaic cell is also known as a solar cell. It is an electric component that can produce electricity when exposed to light particles or photons. This conversion is known as the photovoltaic effect. The first time, its application was found in satellite technology. Then 1980, it is used by the community in form of solar panels, which help them to run their home.
Since then, scientists are working to enhance their capacity which lead to huge solar panels. Various large solar panels projects are working around the work to provide environment-friendly energy to the community.
How photovoltaic cell works
The cell is made of semiconductors that can absorb photons emitted by the sunlight which will generate the flow of electrons to produce electricity. Photons carry solar radiation at a speed of 300,000 kilometers per second.
In the 1920s, when Albert Einstein work on them, he called them “grain of light”. When photons or energy particles hit a semiconductor such as silicon. It releases the electrons from the atom leaving behind free space. And the electrons start moving freely and looking for a fee ‘hole’ to fill.
We all know that to produce electricity, electrons must flow in one direction. This behavior can be achieved using two types of silicon. The first layer which is exposed to sunlight is doped with atoms of phosphorus and it has one extra electron than silicon. The second inner layer is topped with boron which has 1 less electron to fill the space. Now, this sandwich is working as a battery, the first layer has more electrons will work as the negative terminal and a second layer with less electron act as the positive terminal. Then the magnetic field will create at the junction of layers.
Now when the sunlight falls on the cells, the electrons will be excited by photons, they will go to the n-side due to the magnetic field. On the other side, holes will be directed to the p-side. The electric contact will be applied to both sides and start flowing to the electric circuit in the form of electricity. And as result, it produces direct current. An anti-reflecting coating is applied to the Photovoltaic Cell to reduce the photon loss due to surface reflection.
Types of Photovoltaic Cell
There are three types of Photovoltaic Cell
1. Thin-Film Cells
Instead of cutting silicon wafers of around 200 microns3, it is possible to deposit semiconductor material in thin layers only a few microns thick on a substrate such as glass or plastic. Commonly used substances are cadmium telluride and copper indium gallium selenide (CIGS), whose laboratory efficiencies are close to that of silicon, at 22.1% and 23.3%, respectively.
2. Organic Cells
The organic cells use organic polymers and molecules instead of semiconducting minerals are started to be commercially applied. These cells have low conversion efficiency with a short life period but are also a low-cost good alternative.
3. Crystalline Silicon Cells
In the cold processing method, the silicon consists of many crystals and is called polycrystalline. These cells are easy to manufacture and their laboratory efficiency is up to 22%. During the pull-from-melt method, silicon is converted to a large and single-crystal structure and is called monocrystalline. And its laboratory efficiency is up to 26.6%. now due to less silicon’s price, it is easily available for everyone.