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How Electricity is Produced From Solar Panels?
The principle used to generate electricity from the solar panels is the same as that used to generate electricity from the chemical reaction using a standard battery. The basic working of solar panels depends on the semi conductor property of silicon. The silicon is a unique substance that has revolutionized the way electronic appliances work. This property is used to generate electricity from the solar panels. In order to understand how solar panels work we need to understand how silicon works at an atomic level.
Silicon in its pure form i.e. when all the impurities have been removed a silicon atom is bonded with another silicon atom. Since the valency of silicon atom is 8 which means that there are 8 electrons in its outermost orbit. However in its natural state there are only 4 electrons bounded in the outermost orbit. Hence these 4 electrons are able to bond with another 4 electrons with 4 silicon atoms around it. The 4 free electrons that can move around throughout the substance. During the absence of electric potential these free electrons tend to remain close to their parent atoms so that they are at minimum energy level. However when the electric potential is applied across the substance these free electrons receive energy and move direction of the potential difference applied thus producing electric current. However the current produced in a pure semiconductor is quite less because these free electrons wants to remain at minimum energy level possible.
Now let us take an example of a pure silicon semiconductor and introduce a small amount of phosphorus. Now this new atom has five electrons around it. When it bonds with other 4 silicon atoms, its fifth electron is free. But again during the absence of potential difference, the fifth electron is bonded with the phosphorus atom. In presence of potential, these free electrons can move in the direction of the potential difference applied hence generating electric current.
This phosphorus atom is negatively charged this makes the silicon/phosphorus plate negatively charged. In the same way when another substance such as boron is introduced in a pure silicon plate, it becomes positively charged. This is because boron has valency 3 and there is one space left in the boron atom which is called “a hole”. Since this plate hence needs an electron and hence it becomes positively charged.
These 2 positive and negatively charged plates when combined together can now produce electricity. This is when the sun’s energy comes into picture. The solar radiation coming from the sun is used as a trigger to initiate a flow of electric current from positive plate to the negative plate. Now what exactly in the sun’s radiation causes the electrons to agitate? The substance is photon. When this photon falls on the negative plates of the solar panel it knocks off free electrons on the plate. As this electron is loosely attached to its parent atom is freed it can now move around the plate.
However this electron is attracted by the positively charged plate and the electron is bounded again. In the same way when more photons knock off electrons, electricity is generated. The current produced by a single solar cell is very less. However when this current is drawn by the wires, it can power a small motor or other small electronic devices. Many solar cells when combined together can produce sufficient amount of electricity to power a house.
However the main disadvantage of this technology is that manufacturing cost of these panels is very high, also you need large amount of solar panels if your energy requirement is very high. This is the reason why solar panels and electricity produced through them have a very high start up cost. The advantage is that when solar panel when installed can produce electricity virtually free.