Monocrystalline Silicon Cells (or: Mono-Si Cells) are the most efficient commercially viable solar energy collectors.
How are Monocrystalline Silicon Cells manufactured?
Monocrystalline Silicon Cells are often manufactured from a single crystal ingot of high purity.
These ingots are usually grown applying the Czochralski method (which is the crucible drawing process). There are two standard sizes of 12.5 or 15cm (4 or 5 inches).
In order to get cells, the ingot is cut into slices.
Are there any alternative manufacturing methods for mono crystalline cells?
There are other methods for making monocrystalline silicon, such as the edge-defined film-fed growth (EFG) and the string ribbon process.
With the string ribbon process, the cells can be grown at the right thickness which avoids the slicing process and losses.
This makes string ribbon cells cheaper the regular ones. These cells can also be cut squares at no loss of material. Common monocrystalline solar cells are 200-400 um (0.2-0.4mm) thick.
Why is the circular shape cut away?
It is done to make the cells easier to pack and make them less vulnerable during transport. Cell shapes vary from round, semi-round or square.
Monocrystalline Silicon Cells Efficiency
When talking about solar cell efficiencies we have to make a distinction between efficiencies achieved in the lab and efficiencies that are commercially manufactured on a large scale.
The maximum efficiency that can be reached in the lab with a mono crystalline silicon cell is 25%. Higher efficiencies are possible, however it requires multi-junction cells.
Poly crystalline cells have just passed 20% efficiency in the lab, while thin film technologies such as CIGS and CdTe are just below the 20% efficiency. Amorphous silicon currently has the lowest efficiency with around 13%.