How Solar Panels Generate Electricity?

In whatever way electricity is generated, the principle behind how it works is the same. Electricity is a phenomenon that occurs due to the flow of electrons. When it comes to "how solar panels generate electricity", we should once again think of the same principle and apply it here as well. The basic reason due to which there is the flow of electrons is because of the energy that the photons contain in them.


To further enhance your understanding of how solar panels generate electricity, I have compiled here facts from various resources on the internet to help you understand the facts better. Let us first start with the material that is used in these solar panels. These panels are made from a variety of materials among which silicon is the basic element used. For those interested in details, there are actually different types of silicon that is used. Those include amorphous silicon, poly crystalline silicon and mono crystalline silicon. Silicon in its bare form i.e. in the form of the basic element becomes the perfect material to conduct or transmit electrons through it. However, sometimes impurities are added on purpose to enhance this transmission of electrons.


To go even deeper into the chemical nature of the silicon atom and to learn why it is the ideal element for solar panels to generate electricity, read on. There are basically four types of orbitals viz. s, p, d, and f type orbitals. The number of electrons that fill up these orbitals determine the chemical nature of the atom and hence, also whether the atom or the compound eventually formed from the atom is able to transmit electrons effectively or not. Bands are in turn made up of orbitals and it is because of silicon's electron distribution in the bands that makes it so good for use in solar panels. They carry four electrons in their outer bands thus leaving empty space for four more to come and sit in to the empty shells. Remember from the basic atomic laws in chemistry that atoms don't like to leave empty spaces lying around. The aim of every atom that exists is to fill up its empty shells or bands with electrons and hence become stable. Silicon needs four more electrons to do that. The thing that is special about silicon is that it can either give away its four electrons and have completely full inner shells thus becoming stable or gain four electrons. However the compound Si2 is the ideal compound for stabilization as the two silicon atoms can share the four electrons from the other and hence creating a strong sigma bond. Keep in mind, however, that this compound is not polar and hence there are no distribution of charges across the 2 atoms that just combined to form a molecule. Since this bond between the two silicon atoms is so strong, it can last for years to come. Hence, this molecule is used to form the basic structures in solar panels.



However, there is a drawback to this situation. We know that for electricity to flow we need opposite charges to attract and repel the negative electron charge. So the scientists who were conducting research on this found out a way to induce this charge without having to sacrifice the use of silicon. If we go just next to silicon in the periodic table, we will find phosphorus. This element has 5 electrons sitting in its outermost band. It is willing to give them away in order to become stable.


That's why in order to "generate electricity from solar panels", we need to combine the two of them. In that case, we will have 9 electrons shared between the 2 atoms with both atoms stable because they have filled up shells and one free electron lying around for free.
However in order to make this free electron in the above molecule to flow across, we need an opposite charge. So, in that case, if we look at the opposite side of silicon as magnesium in the periodic table, we will find another element with 3 electrons in its outer shell, Boron. This combination between Silicon and Boron will be the positive charge because of the "lack of electrons" and the former, the negative charge because of the excess electron. These 2 combinations form the opposite panels which are joined together in the case of a solar panel in order for it to effectively generate electricity and are both connected to conducting wires to transport or transmit these electrons thus generating electricity.


Now that we have studied the material that is required to make solar panels generate electricity, it is time to consider the sun's rays that are falling on these particles which help in generating electricity utilizing the solar energy advantages. Going into quantum theory, we understand that the light from sun's rays are both particles and waves. The particle part is called as the photon and that's the part we are interested in. With so many photons in a small thin ray of sunlight, when the sun's rays fall on the PV (Photovoltaic) plate, there is a lot of energy coming from the sun and hitting the silicon phosphorus combination.


Because this results in excitation of the one free electron that is left free in the combination, it gets released from the compound and is now "free". However, the silicon boron plate is longing for an electron and sees the opportunity with the single free electron and grabs it. It attracts the free electron to itself and thus the flow of electrons is created. This is in a detailed way "how solar panels generate electricity". The energy generated from this single cell ( a cell is the combination of the two types of plates. ) is enough for nothing. Thus a lot of such cells can be combined huge amounts of electricity.


To give you an idea of how much electricity is generated from a single solar cell, think of your solar powered wrist watch or a simple calculator. That can be powered by this type of solar photovoltaic cell.


Effeciency is a big problem in the solar photovoltaic cells and is one of the factors that scientists are trying to improve upon when it comes to answering the question of "how solar powers generate electricity".


Hoping for a greener future,


Andy.