Experimental results with a 2 kW solar furnace, in a wide range of vaporization rates (0.1-4 g/h), under variable pressure and flow rate of argon, are used with numerical simulation to define key parameters for large scale synthesis of fullerenes with solar energy. The vaporization process is controlled by diffusion in the temperature and pressure ranges 3000-3700 K and 70-250 hPa respectively. In the solar reactor; fullerene yield is governed by the dilution of carbon vapor in argon and the temperature gradient in the cooling zone. Criteria for both parameters are suggested. Consequently, these data, combined with a validated numerical model of the reactor may be used for the design of large-scale solar process.