Polycrystalline silicon, often known as multicrystalline silicon, is a material composed of small silicon crystals or grains. This form of silicon is distinguished by its imperfect crystal lattice structure, which results from numerous grains being fused together during production. It is predominantly utilised in the photovoltaic industry for solar panel construction due to its lower production costs compared to monocrystalline silicon, though it exhibits slightly reduced efficiency in converting sunlight to electricity.
Produced through a casting process, polycrystalline silicon is made by pouring molten silicon into a cast and allowing it to cool. The cooling process is controlled to ensure that crystals form throughout the material, albeit without the single-crystal uniformity of monocrystalline silicon. The presence of grain boundaries, where the crystals meet, affects the electrical properties by increasing electron scattering which can decrease the material’s overall efficiency.
Despite its lower efficiency, the reduced production complexity and cost of polycrystalline silicon make it a popular choice for many solar applications. It is also used in applications where high efficiency is less critical and cost-effectiveness is paramount. Its distinctive blue, speckled appearance helps in visually distinguishing it from other forms of silicon used in solar cell technology.
