PacB Group // How Solar Panels Work and Why We Need Them

Articles

How Solar Panels Work and Why We Need Them

Light from the sun permeates our entire solar system, forming shadows on its most distant object, the dwarf planetoid Pluto and is even visible from galaxies beyond our own Milky Way. For the inhabitants of Earth, the sun provides not only light, but also the life-sustaining warmth that has made it possible to populate most of its land mass. Today, that light and warmth are being leveraged through advanced technologies to produce electricity. The warmth is induced by indirect mechanical means to drive generators, while the light is used to generate an electric current more directly by its interaction with the structures known as solar panels.

These structures have become a common sight on the rooftops of South Africa’s suburban homes, as well as in a larger scale in some of its modern office parks where they are used to service the needs of multiple tenants. Scaleability is one of the major benefits of this technology which, just like wind power, is now being used to create vast “farms” with the ability to augment the output from conventional coal and oil-fired power stations, while offering a means to produce energy without the accompanying harmful emissions.

Furthermore, electricity obtained through the use of solar panels represents the ultimate form of sustainable energy. Although the life of any star is finite, it is measured in billions of years and so, for all intents and purposes, our own sun can be considered as an inexhaustible source of radiant energy. In fact, it was stated at a recent conference of solar energy specialists that there is enough potential energy contained in a single hour of sunlight to meet the needs of the entire planet for a whole year. That is serious sustainability according to anyone’s definition, and is just one of the reasons why we should all consider installing some of these eco-friendly solar panels.

So, how does this seemingly miraculous transformation of light into electrical energy actually occur? The conversion process is known as the photovoltaic effect, and it was first observed by a French physicist named Becquerel back in 1839. He noticed that each time light struck a platinum electrode immersed in an acidic solution of silver chloride, an electric current was produced. Later studies were destined to provide the basis for the construction of modern solar panels when an English electrical engineer observed the same effect when he exposed selenium rods to the light of a nearby candle.

Neither of these gentlemen could, of course, explain the phenomenon, which we now know is due to the ability of photons to displace electrons from certain materials known as semiconductors, which include such substances as silicon, germanium, lanthanum, selenium, and their various compounds. They are used widely in the manufacture of transistors and lasers, as well as the individual photovoltaic cells that are connected in series to form solar panels.

Today, engineers use a technique called doping, introducing impurities to modify semiconductor properties. A typical cell consists of two differently doped layers of silicon in which the upper layer is exposed to sunlight and contains an excess of electrons, whilst the concealed lower layer is electron-deficient. Electrons displaced by incoming photons travel along a connecting wire to the lower layer where they are captured to create an opposing flow of direct current with a voltage of approximately 0.5v. Typically, 36 of these are required for a 12v panel, and several of these must then be assembled into a suitably large array with sufficient output to meet the power needs of any given end user.

In the absence of any moving parts that might become worn, the solar panels require little maintenance beyond ensuring they are kept clean, so as not to block out the sunlight. A complete installation requires an inverter, storage batteries, and connection to the distribution board, so should always be left to a professional.