Small silicon spheres, less than 200 um in diameter, are desirable for use in forming solar panels. To make such small spheres, a large-area glass substrate has etched in its surface millions of identical indentations, such as having diameters less than 200 um. A silicon ink, formed of a fluid containing nanoparticles of milled silicon, is then deposited over the substrate to completely fill the indentations, and the excess ink is removed. The ink is heated to evaporate the fluid and melt the silicon nanoparticles. A photonic system is used to rapidly melt the silicon. The melted silicon forms a sphere in each indentation by surface tension. Since the density of the silicon in the ink and the volume of each indentation are well defined, the volume of each sphere is well defined. The substrates are reusable. Hundreds of millions of spheres may be produced per minute using the process.