2, Helios Resource Ltd., Saransk, , Russian Federation
The most important aspect of photovoltaics sustainable development is the use of environmentally friendly, low-cost materials and technologies for manufacturing PV station components. The main material for solar cell production is silicon.
The paper presents the research results of a new technology for solar-grade silicon production by the method of plasma-chemical purification of metallurgical-grade silicon with the use of magnetohydrodynamic mixing, based on plasma interaction with the silicon melt surface in the crucible. The method ensures the ecological safety and scalability of the technology, the combination of the purification process and the subsequent direct crystallization of silicon melt into one process, the silicon cost reduction.
The paper studies the purification process regularities by the method of mathematical modeling:
the effect of the plasma flow rate on the surface mass transfer rate of silicon melt;
the dependence of the impurity diffusion in silicon on the surface mass transfer rate;
the effect of magnetohydrodynamic mixing of silicon melt on silicon purification process.
The analysis of the cost of silicon produced by the investigated method was carried out.
Comsol calculation programs are used for mathematical modeling.
The research results are as follows:
the interconnection between the plasma flow rate and the surface mass transfer rate is established;
the dependence of the diffusion rate of impurities (metals, phosphorus, boron) on the surface mass transfer rate is established;
the processes of silicon melt movement under the conditions of its interconnection with plasma and the effect of magnetohydrodynamic mixing on the processes of silicon purification are investigated.
It is established that the cost of silicon obtained as a result of the new technical process amounts to no more than USD 9.0 per kg.