Capturing solar energy for efficient hydrogen generation is a sustainable technology strategy for renewable energy storage and application. However, its practical deployment for distributed hydrogen generation is hindered due to the limits of low efficiency of single photocatalyst and gas crossover/mixing. Here we report a prototype of integrated device design by incorporating a photocatalytic regeneration cell with a redox flow cell through the linkage of redox mediator for high efficiency and low-cost hydrogen production. The redox mediator ions are continuously regenerated through photochemical reduction provide electrons for subsequent H₂ production in either continuous or intermittent modes. This novel design enables utilization of single band photocatalyst for high efficient solar harvest, decouple H₂ and O₂ redox reactions, and possibly lower the cost of H₂ generation to less than $2/gge. Figure 1 shows voltage profiles of long term H₂ generation for 8hrs operation at a current density of 10 mA/cm² (black) and mediator concentration change during the process (blue).