• Your cart is empty


How Silicon Makes its Way in Solar Panels?

Silicon is an important and an essential element of solar panels. The discovery of the silicon and its nature/behavior when mixed with other silicon atoms and useful interaction with other elements has been a readily available knowledge base in the invention of solar panels. In this article, we are going to explore more about silicon as an element by itself, its chemical properties, covalent bonds formed by silicon and finally its journey to make up a solar cell.

Silicon makes its way in solar panels due to the exhibition of an extraordinary chemical property that it readily possesses in its natural state. Silicon in its native, crystalline form is apt for solar panel design and implementation, fabrication and ultimately assists in the solar panels' manufacturing processes.

Silicon as an element has 14 electrons (negative charge) which are distributed in different shells. First two shells are filled to the full capacity with 2 and 8 electrons respectively. The special property of silicon is displayed by an incompletely/partially or exactly half-filled shell of 4 electrons.

Because of exactly half filled shell, silicon atom cannot afford to lose electrons, nor can it that easily gains electrons. The best thing that can happen if we look at one particular silicon atom is that it can share electrons with four other silicon atoms and so on. Formation of bonds due to sharing of electrons is called covalent bonds. Thus crystalline silicon is purely covalent in nature. This nature of the crystalline silicon makes it best put to use for application in design and manufacturing of a solar cell which are tightly coupled into a solar panel product.

However, remember that we are talking about solar panels which convert light to electricity. But silicon atom in its pure form is incapable of conducting electricity. This is due to covalent nature of bonds inside crystalline silicon.

A known remedy to eliminate this problem is that silicon is forced to conduct electricity in a solar panel by doping it with impurities like phosphorous. Doping is done with least concentration possible (one doping atom in a million silicon atoms). Here phosphorus being pentavalent (5 electrons in outer shell), has one electron left loose for conduction of electricity through its free movement to thus formed n-type semiconductor crystal. This is achieved in spite of utilizing the rest four of them to form covalent bonds with silicon atoms.

All this effort and process of doping is done to make silicon conductive easily, with least of efforts. Or else another outcome or alternative to doping is that we need to supply a lot of energy (mainly heat energy) to break covalent bonds. This in turn would cause the same effect like doping. Supply of enormous amount of energy would be required to set electrons free to wander within the crystal.

But in the above stated process of supplying of heat energy, an electron that is available for conduction comes from the silicon atom itself (and not any impurity). When pentavalent atoms are doped into pure crystalline form of silicon available naturally in the earth's crust, it forms n-type crystal. The same is true when trivalent atoms like Boron are added as impurities. However, altogether it forms a different type of crystal known as p-type crystal.

It is quite normal to get confused here, especially because doping atoms are nothing but impurities. We have always believed that "impurities" are bad and possible elimination of them to a great extent works wonders in any system. But you have to understand that the silicon crystals would fail to conduct electricity in their absence. Such is an importance of a strategy like doping. Doping is therefore an essential process in the fabrication of the solar panels.

Related articles