Wafers for solar PV

Silicon wafers are thin slices of crystalline silicon that serve as the substrate for fabricating solar cells. They are usually made from high purity silicon material that is melted and crystallized into ingots, then sliced into thin disks. The wafers are then cleaned, textured, doped and coated with various layers to form the solar cell structure.

Silicon wafers for solar PV applications have several advantages, such as high efficiency, long-term stability, low cost and abundant availability. However, the carbon footprint associated with the purchase of high purity liquid argon, for the inert purge gas, contains one of the highest CO₂ equivalent footprints.

Argon gas and silicon wafers

High purity argon (better than 99.9998%) is used as a shield gas in the production of silicon ingots, to be fabricated into wafers, for solar cells and micro-electronic devices. The argon is used to control the gaseous impurity levels present during the manufacturing process to an acceptable level. In response to the trend in the solar industry for yet higher efficiency solar panels, the argon purge gas flows used in the CZ Ingot Pullers have increased by up to 100% in the last 5-10 years, with current purge flows in the 80-100 l/min range. Higher purge gas flows translate directly into silicon wafers with fewer defects and improved carrier lifetimes resulting in solar cells with improved efficiency.

There is also a growing requirement for all elements of the Solar PV supply chain to reduce their carbon footprint with some geographies and energy companies, for example in Europe, moving to only approving panels for sale and installation with a low manufactured carbon footprint.

For manufacturers faced with increasing argon usage, rising argon prices and having to reduce their CO₂ footprint, investing in the Gas Recovery and Recycle Limited ArgonØ argon recycling systems can reduce the facility argon usage by at least 95%, and is a highly attractive proposition saving both cost and CO₂ footprint and improving sustainability.