The Sunday Mail
Takaendesa Denhere
When I was young, my mind would stretch to the limits as l tried to figure out how solar panels produce electricity. From my childhood up to the time when l could do my own research, nobody seemed to know or care to explain it to me. It seemed so complicated — how the panel turned sunlight into energy, how the solar cells captured the light. My head would spin round and round, leaving me very curious.
But now l have the answer.
The generation of electricity from solar panels is not a mystery. Solar panels are known as photo-voltaics (PVs). Photo comes from the Greek root word phos, meaning light and volt is from the pioneer of the study of electricity, Alessandro Volta. The electricity from the solar is also known as photovoltaic electricity. Nevertheless, I am going to stick with the common term “solar panels” which many of us are familiar with.
A solar panel is a flat surfaced panel which is directed to the sun so that it captures the radiation emitted by the sun. A panel is made up of solar cells — these are semi-conductor devices that convert solar radiation into electricity and there are many of them on each panel.
The cells are made of a natural element, silicon, which becomes charged electrically when subjected to sunlight. Solar cells are made of at least two layers of semi-conductor material. One layer has a positive charge, the other one has a negative charge. When light enters the cell, some of the photons (tiny particles contained in light from the sun) from the light are absorbed by the semi-conductor atoms, freeing electrons from the cell’s negative layer to flow through an external circuit and back into the positive layer. This flow of electrons produces electric current which is trafficked through electric cables.
There are different types of solar cells and normally the difference determines the efficiency and the prices of the panels. However, I am going to keep it simple and straight-forward by focusing on conventional types of solar panels only.
The silicon solar panels come as crystalline and poly-crystalline panels. They perform best in low light areas. They are the most efficient on the market and are expensive as well. On efficiency, they top at a staggering 33 percent.
Thin film solar panels are more flexible when compared to their silicon counterparts. They are less efficient and less expensive. Their efficiency ranges from 10 to 19 percent.
To harvest the most energy, there are three factors. For large scale generation of solar electricity, the solar panels are connected together into a solar array. The more panels on an array, the more electricity produced. Secondly, sun intensity determines energy production. If there is no cloud cover, the amount of sunlight directly increases the output of electrical energy.
Sun track is the third factor. More energy is collected by the end of the day if the solar panel is installed with a tracker that follows the sun.
There are two types of sun trackers, the one-axis tracker that follows the sun from east to west during the day and the two-axis tracker, which follows the sun from east to west during the day.
When compared to the fixed design, a sun-tracker can increase the energy yield by up to 40 percent over the year.
During the night, it positions itself for the next morning’ sun. By this design, the sun incidence angle could be fixed to meet the maximum power.
Solar panels are directed at solar south in the northern hemisphere and solar north in the southern hemisphere (these are slightly different than magnetic compass north-south directions) at an angle dictated by the geographic location and latitude of where they are to be installed.
Typically, the angle of the solar array is set within a range of between site-latitude-plus 15 degrees and site-latitude-minus 15 degrees, depending on whether a slight winter or summer bias is desirable in the system. Many solar arrays are placed at an angle equal to the site latitude with no bias for seasonal periods.
Solar panels are used to generate electricity for domestic and commercial use. On the commercial basis, there are solar farms that occupy vast tracts of land to accommodate thousands of solar panel arrays. Electricity is then trafficked to the substation which then distributes the energy to households and industries.
Despite Germany’s latitude that does not furnish her with a lot of sunshine, the country is leading the world in using this form of technology,
It must be noted that to generate solar electricity, it is the light that is needed, not the heat. Heat does not matter at all. In fact its place is in solar heating systems, that is where they only work. Normally, if the heat is too much, the efficiency of the solar panel is actually compromised.
There are some bizarre theories that claim that solar panels can work at night. No, they do not work at night because the only light that is available at night is moonlight. To produce electricity from solar panels, direct sunlight is needed.
Unlike the sun, the moon does not generate its own light energy.
The moonlight is basically the sunlight reflecting on the moon surface. It does not contain the required energy to knock out the electron from the bond.
Takaendesa Denhere is an independent researcher who writes on renewable energy. For feedback contact him on his email: [email protected]
