Silicon Solar Cells
How Do Silicon Solar Cells Work?
The basic component of a solar cell is pure silicon, which has been used as an electrical component for decades. Silicon solar panels are often referred to as '1st generation' panels, as the silicon solar cell technology gained ground already in the 1950s. Currently, over 90% of the current solar cell market is based on silicon.
Pure crystalline silicon is a poor conductor of electricity as it is a semiconductor material at its core. To address this issue, the silicon in a solar cell has impurities—meaning that other atoms are purposefully mixed in with the silicon atoms in order to improve silicon’s ability to capture the sun’s energy and convert it into electricity.
For instance, an atom of gallium has one less electron than an atom of silicon, while an arsenic atom has one electron more. When arsenic atoms are put in between lots of silicon atoms, there will be extra electrons in the structure; so an electron-rich layer will be created.
When using gallium atoms instead, there will be a lack of electrons, meaning that an electron-poor layer will be produced. In a solar cell, the layers are positioned next to each other and that way an electric field is created. When the sunlight hits the solar cell, the energy stimulates electrons that leave holes behind. These migrate to the electrodes in the cell because of the presence of the electric field. In this way, electricity is generated.
What Are Silicon Solar Cells Used For?
Back in the days, silicon solar panels used to be rather expensive, as very high-quality silicon was required for creating them. Also, the procedure of purification of silicone before interfering it with gallium and arsenic atoms used to be time-consuming and costly.
Fortunately, the development of technology soon allowed the use of cheaper and lower quality silicon. As a result, silicon solar cells are now more affordable, especially with the support of government subsidies.
The Limitations of Silicon Solar Cells
Silicon panels are not ideal for transportation since they are quite fragile and rigid. Another complication is that the parts are still fairly expensive, in comparison to some of the alternative options in the solar technology field.
Types of Silicon Solar Cells
Monocrystalline Solar Cells
Monocrystalline solar cells, also called "single crystalline" cells are easily identified by their dark black colour. Monocrystalline solar cells are made from a very pure type of silicon, which makes them the most efficient material for converting sunlight into electricity.
In addition, monocrystalline solar cells are also the most space-efficient. Another advantage of monocrystalline cells is that they last the longest of all types - many manufacturers offer warranties of up to 25 years on these types of photovoltaic systems.
All these superior benefits come with a hefty price tag – in fact, monocrystalline cells are the most expensive option, mostly because the four sided cutting process results in wasting a lot of silicon, sometimes more than half. The cheaper alternatives for consumers would be polycrystalline- or film cells.
Polycrystalline Solar Cells
Polycrystalline solar cells, also known as polysilicon and multi-silicon cells, were the first solar cells presented to the industry, in the beginning of the 1980s. Polycrystalline cells do not undergo the cutting process used for monocrystalline cells. Instead, the silicon is melted and poured into a square mould, hence the square shape of polycrystalline.
This makes polycrystalline solar cells much more affordable, as hardly any silicon is wasted during the manufacturing process. On the minus side, they are less efficient and require more space than single crystalline cells, due to the fact that the purity level is lower in polycrystalline cells.
Another disadvantage is that polycrystalline has lower heat tolerance than monocrystalline, meaning that they are unable to function as efficiently in high temperatures.
Amorphous Solar Cells
The word 'amorphous' literally means shapeless. The silicon is not structured or crystallised on a molecular level as many other types of silicon-based solar cells are. In the past, amorphous solar cells were used for smaller-scale applications, such as pocket calculators, because their power output was relatively low.
However, by stacking several amorphous solar cells on top of each other, their performance increased significantly (up to 8%). Amorphous silicon solar panels are a powerful and emerging line of photovoltaic systems that differ from crystalline silicon cells in terms of their output, structure, and manufacture. The material costs are reduced since amorphous silicon only requires about 1% of the silicon that would have been used to produce a crystalline-silicon based solar cell.
The development process of amorphous silicon solar panels has made them more flexible and lightweight, which makes the transportation and installation of the panels less risky. A flexible thin-film module renders amorphous solar cells suitable even for curved surfaces.
One of the drawbacks is the lower efficiency rate of amorphous thin-film solar cells. However, the technology is new, and efficiency rates are thought to increase with technological breakthroughs in the near future.
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