Integration of concentrated solar energy into the pyrometallurgical Zn production process as clean source of high-temperature process heat could significantly reduce fossil fuels consumption and its concomitant CO2 emissions. The solar-driven carbothermal reduction of ZnO is investigated using a 10-kW(th) solar reactor featuring two cavities, the upper one serving as the solar absorber and the lower one containing a packed-bed of ZnO and beech charcoal as the biogenic reducing agent. Experimentation in a high-flux solar simulator is carried out under radiative fluxes of 2300-2890 suns, yielding a peak solar-to-chemical energy conversion efficiency of 18.4%. The reactor performance under variable operating conditions is analyzed via a dynamic numerical model coupling heat transfer with chemical kinetics. The model is validated by comparison to the experimental data obtained with the 10-kW(th) packed-bed solar reactor and further applied to predict the effect of incorporating semi-continuous feeding of reactants on the process efficiency. (c) 2016 American Institute of Chemical Engineers AIChE J, 62: 4586-4594, 2016