Process for the preparation of usable silicon for solar cells

The invention relates to a process for producing silicon which can be used for solar cells, by reduction of SiO2 with carbon in an arc. This involves preparing the SiO2 by SiO2-containing mineral materials with admixtures of Al2O3 and oxides of alkali metals and alkaline earth metals being converted into the glass phase (6) by melting, which phase is then converted into a glass fibre structure (11). The glass fibre (11) is then subjected, without tempering, to a phase-separation/leaching process and converted into a porous SiO2 body (Figures 1 and 2). The process according to the invention makes it possible to obtain an SiO2 material for the arc process, which, despite the use of cheap starting materials, has the high purity required for the fabrication of solar cells.