Silicon-based solar modules fall into two categories: Monocrystalline and Multicrystalline. In each category, the polysilicon must be converted into a crystalline structure. A monocrystalline ingot is comprised of one large crystal structure, which yields a uniform color and texture throughout the ingot. A multicrystalline ingot contains numerous smaller silicon crystals and often has a mottled or flecked appearance.
KEMI Silicon, Inc. supplies monocrystalline-based technology because this solution produces solar cells and modules with a higher efficiency conversion rate of sunlight to electricity. The most common technology used in the production of ingots for monocrystalline solar cells is based on a technique called the Czochralski Process.
In this process a silicon seed crystal at the end of a metal rod is lowered into a quartz crucible of molten silicon liquid. As the rod and seed crystal are slowly pulled out of the crucible, a single cylindrical silicon crystal forms on the seed crystal. The production of monocrystalline ingot requires precise specifications and careful monitoring to ensure uniform crystal growth and contaminant-free ingots. Completing a single cylindrical silicon crystal ingot takes between 36 and 40 hours and yields an ingot of approximately 2 meters long and 6 to 8 inches in diameter.