Studying biohydrogen production via sequential dark- and photo-fermentation at the pilot-scale is of practical significance. In this study, an 11 m(3) pilot-scale bioreactor was used to investigate biohydrogen production via dark- and photo-fermentation. Solar energy was used to provide heat, illumination, and power for the bioreactor, thereby reducing biohydrogen production cost greatly and indirectly reducing carbon emissions. Gas production rates were 96.30 mol/m(3)-d and 224.68 mol/m(3)-d via dark- and photo-fermentation, respectively. The pH values and oxidation-reduction potential varied from 5.13 to 5.92 and -382 mV to -490 mV, respectively. Low relative average deviations between on-line and off-line data show efficient stability. This automated reactor system could potentially contribute industrialization of biohydrogen production. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.