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in the sense that the wastes must be disposed off. In the current work, the term “waste”
means off grade material that is not or cannot be used for its intended purposes. In the
metallurgical silicon world, this “waste” is off grade silicon dust that is generated from
the grinding processes that cannot be sold or used as a feedstock in the polysilicon or
chemical markets. In the world of solar wafer manufacturing, this “waste” is kerf loss
from the wafering process that also cannot be reused in the Photovoltaic value chain.
The amount of waste built into the Photovoltaic value chain is growing with each
GW of installed solar capacity yet an outsider looking in will find these wastes
somewhat obscure. As the solar industry transitions from subsidized to free market
dynamics the growth of these wastes are seen equally as persistent.
It is clear that there are wastes in every industrial process and almost all industries
attempt to reduce or mitigate these wastes and convert them into valuable products. In
the case of energy intensive industries, the recycling of waste, for which energy was
expended to produce, become valuable low hanging fruits to reduce costs and disburse
fixed costs. In the case of silicon wastes there are two main sources of wastes in the PV
value chain. These are
(i) Silicon grinding fines
Grinding wastes occur as the off size produced during the grinding operations
of metallurgical silicon to produce on spec silicon powder feedstock for the
Trichlorosilane and Methylchorosilane processes. These wastes are generated
from the milling and grinding process steps and vary in quantity as a function
of the technology used, equipment age and wear, process parameters and size
and characteristics of the material processed. The material is generally lower
Figure 2 MG silicon and PV value chain
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