How does a solar cell work?


The solar cells can be used as the alternative source of electricity. As all know the fossil fuels and other sources of energy such as coal which we have been utilizing so far for making electricity is decreasing day by day. The solar power can be used to solve this problem. Since the energy provided by the sun is limitless without generating any waste, this can serve the purpose perfectly.

The mechanism that converts the sunlight energy into electricity is known as the solar cell. Rows of solar cells are placed together to create solar panels, photovoltaic ranges and solar modules.

The photovoltaic (PV) cells that are present in the solar panels will directly convert the sunlight into electricity. These PV cells are made of semiconductors such as silicon. Now when the light particles comprised of photons that are present in the sunlight strike the solar panel, part of it is sucked up by the PV cell. Now the electrons are knocked free and this flow of electrons generates a current. When a metal contact is placed on top of these PV cells, the current can be drawn and used for powering electrical devices.

Solar panels were first used for military applications such as powering the satellites that were launched into space as far back as 1948. To start with, the efficiency of the solar cells was 1% but currently the efficiency levels have increased to 40.7 % as per the US Department of Energy statistics (these are for civilian uses).

The basic circuit of a solar cell

Mainly two separate pieces of silicon are joined together along with an induced electrical field. The electrical field is induced when the N-type and the P-type of silicon will come together. The N-type layer has a huge amount of free electrons. The opposite side of the layer is called as P-type; this side has a shortage of electrons. The shortage of electron in this side is described as holes. These two layers are now in close proximity and the free electrons from the N layer to the P layer inducing the electrical field. This is the basic circuit present in the solar cell.

As the sun’s rays hit these cells, the electron pairs will be broken apart. When this happens close to the induced electrical field, and then a way is given to the electrons to flow in a particular direction, the electron flow will provide us with a current. While, the electric field of the PV cell will provide the voltage. The product of current and voltage will provide us with the power that is required for generating energy for the devices that are connected to the solar panels.

One of the problems with using silicon as a semiconductor is that it is an extremely shiny substance and can bounce back the energy of the sun. To prevent this from happening, an antireflective coating is also applied on the cells and the panels. The last component is known as the glass plate that will protect the cells from other elements of the nature such as wind, dust and water.

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