Solar Energy Articles

Anatomy of a Solar Panel

Solar panels and the information we have about them is the fact that silicon (doped) is used in their construction. Doping alters the properties which is useful to induce voltage in the doped silicon. The interesting part begins after the silicon is doped. All the action that happens inside the solar cells is based upon some properties of doped silicon. The requirement for this is that two differently doped silicon wafers (p-type and n-type) must be put together. In this article, we are going to explore the anatomy of the solar panel keeping in mind the construction and design that we have read before.

Before now, the two silicon wafers of either types of doping when are isolation, are incapable of producing electric current. This is due to the fact that these standalone doped silicon crystals are electrically neutral and there is an absence of electric field within the wafer to cause retention or movement of electrons. The interesting part and all the action due to the photoelectric effect happens when you put together two differently doped silicon wafers in conjunction. As a simple fact to be understood, just understand that the solar cell would not work when there is no electric field present.

The formation of the electric field takes place when n-type and p-type silicon come in contact with each other. Physically, there is an excess of electrons in n-type crystal and deficiency of electrons in p-type crystal. This electron concentration difference governs the basic principle of formation of electric field. Upon joining, there is a rush of electrons from n-type crystal to p-type crystal.

One important fact to be considered, an atom is always neutral in nature, or rather; there are equal number of electrons (negative charge) and protons (positive charge). When there is migration of electrons as described above, there is an obvious imbalance of positive-negative charge inside the individual crystals that form p-n junction. N-type crystal becomes positively charged and vice versa for the p-type crystal. This charge imbalance in either of the crystals causes the formation of electric field across the p-n junction. Remember that the direction of electric field is from n-type crystal (positive) to p-type (negative). This electric field opposes further migration of electrons across junction.

Interaction between photon-electron: Photons contain energy. When they strike electrons, energy is imparted from a proton to an electron. When photons strike the electron-hole pairs of the solar panels, the electrons and holes overcome the potential barrier caused due to the induced electric field at the junction, electrons flow towards the p-type where they have no more holes to combine. When connected to a circuitry, electrons recombine with holes in the n-type through the external circuitry.

Flow of electrons in a closed loop constitutes of an electric current, as we all understand. The induced voltage is present at the junction due to the electric field. In a way, we can say that the electric current is constituted in the solar cells against the induced voltage.

Power is a product of voltage and electric current. Since we have both the parameters present, we also have power. Remember that power in this case is generated inside the solar cell due to the photovoltaic effect. Energy is thus produced by an overall system that is nothing but an assembly of interconnected solar cells to make up a solar panel. Law of conservation of energy: If you are perplexed by the fact that here energy is created from nothing; then think twice! Remember that law of conservation of energy always holds true. In this case also energy is not created. It is just transferred from one form to another (in this case from photon to solar panel output). In simple terms, light energy is converted to electrical energy. This electric energy can be used for the variety of applications already discussed.

Anatomy of a solar panel surely is interesting. A lot of research is going on though to maintain the standards in terms of efficiency and to minimize losses in a solar cell.

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