Solar Energy

The solar technology industry has approximately 60 years of cumulative research, and still, 90% of commercial photovoltaics are crystalline silicon (c-Si). Within crystalline silicon, there is single-crystal, also known as monocrystalline (sc-Si), and multicrystalline (mc-Si). Monocrystalline has higher efficiency and is approximately 20-30% more expensive than multicrystalline. Monocrystalline silicon is made using crystal growth technology, specifically through a method known as the Czochralski process that grows single crystals of silicon into large ingots. In comparison, mc-Si requires silicon to be melted into a cast, producing many randomly oriented crystals. A downside of crystalline silicon is its low ability to absorb light. To compensate, a thick, brittle wafer of silicon is used in solar cells to increase the module’s efficiency.

Solar grade silicon also requires ultra-high purity. Electronic grade silicon is 99.99% pure, while solar grade silicon is 99.9999999% pure. This process requires multiple refinement and purification methods at high temperatures of 1000°C – 2000°C. Despite this, crystalline silicon will likely remain the leading technology due to the many years invested in research and the abundance of silicon (It is made from sand!)

Some companies have worked to pioneer other technologies. The progress of solar technology has mainly improved solar modules’ efficiency by exploring various other materials. It should be noted that for some of the emerging technologies, such as perovskites, GaAs or hybrid, only small modules have been created. These technologies face challenges with the scale of the material costs and methods of production. In most cases, it is difficult to increase production scale while maintaining the quality of the modules.

Thin-film technology in solar systems typically has a lower cost of raw materials in an automated manufacturing process; however, the trade-off is lower efficiency. Two types of thin-film PV include CIGS and CdTe. These technologies have complex chemistry, which makes it difficult to produce high-quality, large-area panels. This technology is also susceptible to moisture and oxygen, requiring the panels to have a more strict hermetic encapsulation procedure to ensure the panels’ efficiency and reliability for 25-years. The use of toxic elements, such as cadmium, and rare elements, such as tellurium/indium, limit large-scale deployment potential.

Cadmium Telluride (CdTe) is a thin-film photovoltaic technology used in some Mitrex glass panels. It is the second most popular photovoltaic technology next to silicon due to the ease of manufacturing and its low cost. Silicon solar cells have a fixed size because they must be made from wafers; however, we are not constrained by this limitation with CdTe technology. The limitless size options for thin-film allow us to maximize the potential of every piece of glass without wasted space. It is also possible to create strips of thin-film areas and adjust the spaces between them to make more transparent glass products. Unfortunately, the efficiency of thin-film solar is not on par with silicon technology. Also, as previously mentioned, the rare and toxic materials used to make this technology further limit the potential of mass-scale production. Extra care must be applied to the disposal and recycling of this product. Overall, thin-film solar technology benefits have allowed these systems to remain a prevalent option, as they allow for transparency and size variations.