PV System

PV SYSTEM

The photovoltaic effect :

How do solar panels work?

The base component of solar panels is silicon. When silicon is stripped of its impurities, it becomes a sufficiently neutral platform for the transmission of electrons. Silicon has properties on the atomic scale making it all the more attractive for the creation of solar panels.

All silicon’s valence electrons participate in chemical bonding so there are no conduction electrons in pure silicon, unlike in metal.On the external surface of a pure silicon atom electrons do not move from one atom to another.

To introduce an element of conductivity the silicon is doctored by introducing other atoms which are called impurities (phosphorous and boron). Its conductivity increases as the temperature rises making it a semi-conductor.

What happens if phosphorous atoms with 5 valence electrons are introduced ?

The 4 electrons of the phosphorous atom bond with the silicon atom, thus leaving one to ensure conductivity. This is an N-type doping, N for negative as conductivity is the result of the presence of the extra electrons.

What happens if boron atoms with 3 valence electrons are introduced ?

The 3 electrons of the boron atom bond with the silicon atom resulting in a “lack” of an electron known as a positive hole. The valence electrons move in to fill these holes themselves freeing holes as they do so. This is a P-type doping as conductivity is effected via these holes.

The two plates which make up a solar panel are doctored in different ways so that electricity may flow. The surface separating these plates is called the junction which is constituted of conductive wires.

With the two plates in place, the natural light of the sun sends out numerous particles of energy, but those which interest us the most are photons. Through the rays of sunlight, the photons bombard the negative plate (silicon/phosphorous) of the solar panel.

The free electrons of the negative plate (silicon/phosphorous) cross the junction towards the positive plate (silicon/boron) and electricity is produced. This is the photovoltaic effect!

The energy produced is direct current which cannot be used by the electrical appliances in the home.

The photovoltaic principle resides in the transformation of the sun’s energy in the form of light so as to provide the consumer with electricity.

The energy produced by the panels is direct current. It is present as soon as there is light and the current increases in line with the intensity of the light.