We report on a novel high-efficiency electrochemical approach for the production of molecular hydrogen that is indirectly powered by sunlight with through the use of photovoltaic (PV) arrays. Water splitting coupled with organic chemical contaminant oxidation under very mild conditions is achieved with the PV-powered electrolysis cell that is based on the coupling of bismuth-doped titanium dioxide semiconductor anodes (BiOx-TiO2) with simple stainless steel cathodes (SS). In this hybrid system, the production of molecular oxygen at the anode is suppressed by the simultaneous oxidation and mineralization of organic chemicals present in water. Anodic oxidation of organic contaminants has a synergistic effect on cathodic hydrogen gas production that results in a maximum 53 % increase in H2 production energy efficiency at the pH of natural waters with low background electrolyte concentrations. Overall energy efficiencies are found to be comparable to industrial-scale electrolysis that, in contrast, is carried out under high electrolyte concentrations and very basic conditions, pH 14.