Silicon has been used as an electrical component for many years. It was while someone was trying to improve this element’s ability to conduct electricity (by adding impurities into its structure and then exposing it to the sun) that the silicon solar cell was born. This happened in 1953. Since then, time, money and effort has made silicon the most well-known and established solar technology in the world. Silicon solar panels are sometimes referred to “first generation” panels.
How do they work?
Silicon is a semiconductor material. When it is doped with the impurities gallium and arsenic its ability to capture the sun’s energy and convert it into electricity is improved considerably. An atom of gallium has one less electron than an atom of silicon and an arsenic atom has one electron more. When arsenic atoms are put in between lots of silicon atoms, there are extra electrons in the structure so it creates an overall electron-rich layer. When gallium atoms are used instead, there is a lack of electrons so an electron-poor layer is produced.
In a solar cell, the layers are placed next to each other and an electric field is created. When the sunlight hits the solar cell, the energy excites electrons that leave behind holes. These migrate to the electrodes in the cell because of the presence of the electric field. In this way electricity is produced.
What is it used for?
Silicon solar cells gained much attention during the space race during the late 1950s and 1960s. Spaceships and satellites up in space need a lot of power to run the electrical equipment inside, but batteries sent up with them run out within days. By using solar cells connected up to make big solar panels they can power the equipment indefinitely.
Silicon solar panels used to be very expensive to make as very high quality silicon was required. Before doping it with gallium and asrenic atoms, the silicon needs to be very pure and this requires a long process involving high temperatures which costs money. Several decades ago, the only people who could afford to buy silicon solar cells were the people spending billions of dollars on sending something into space.
Lucikly, development work soon allowed solar cells to be made with lower quality silicon and cheaper materials so they became competitive in remote locations where traditional connection with mains electricity was difficult and costly, for example telephone connections in the Australian outback.
Nowadays, silicon solar cells are a little more affordable, especially with government subsidies in place. They are also highly efficient with the record efficiency around 24%. Currently, over 90% of the current solar cell market is based on silicon.
What are the limitations?
Silicon panels are rigid and can be fragile, not good for transporting solar cells to remote locations on bad roads. The components are still relatively expensive compared to some of the other options in the solar power market.