What is a monocrystalline solar panel?
It is called monocrystalline because of how it is made or more appropriately, how what it is made from i.e. it is made out of a single crystal (of silicon).
How monocrystalline solar panels are made?
Unlike the polycrystalline panel which is gotten from many silicon crystals obtained melted and directly cooled, the production of a monocrystalline panel involves a more complex process ‘the Czochralski Growth’ .
After obtaining the silicon rocks from its parent rock, it is melted in something like an enclosed flask called the ‘Czochralski Growth Apparatus’. This flask has a heater in its innermost layer with a graphite bowl that contains the silicon rocks. The innermost layer is succeeded by another layer called the heat shield located in a space called the chamber.
Once the silicon is melted, a certain material called the ‘seed crystal’ is dipped into fluid and is pulled back up while rotating. The seed crystal continues to rotate as it moves up, while the graphite bowl simultaneously lowers itself, thus creating a solid cylindrical ingot of silicon around the seed crystal. The ingot might be larger than the desired diameter, but it can be trimmed to a desired size.
Large-sized ingot would not do us any good. Therefore, the ingot is sliced into thin layers using a 100-200-micron thick high-grade steel wire connected to rotating rollers cuts the ingot into roughly-surfaced wafers. To remove the rough surfaces several wafers are lapped on both sides in between to counter-rotating pad, this is called ‘lapping’. Though lapping helps to smoothen the surface of the wafer, it degrades the crystal structure of the silicon surface of the wafer. However, a process called ‘etching’ is employed to restore this and improve the crystal structure. Etching is done by immersing the wafer into any suitable etchant such as; KOH or HF.
The surface of the panel is then polished using an ultra-fine slurry to obtain a smooth wafer.
Having discussed how the various Crystalline panels are made we have a good ground to discuss the major differences between them. As we move on we would consider different points in analyzing the two types of technology.
