Silicon wafers are produced by slicing silicon ingot (as shown on the picture). Conventional, monocrystalline silicon ingots are produced by pulling out from graphite crucible. Graphite crucibles are known to have low strength, short lifetimes, and a high risk of silicon leakage because the crucibles are prone to cracking during the heating process.
Yingli has successfully completed trial production of monocrystalline ingots using new material technology. They are using crucibles made from a carbon-carbon (C-C) composite material. Initial estimates suggest that the new material could reduce manufacturing costs by nearly US$0.01 per watt. This is few percent of panel production cost already.
C-C composite crucibles are not as vulnerable as graphite because they are made from a reinforced carbon fiber matrix that is low-density, high-strength, with high thermal conductivity, thermal shock resistance, and dimensional stability. The new crucibles can improve the stability of crystal pulling, and increase the utilization rate of monocrystalline silicon ingots by approximately 3%.