A redox cell rebalance system is provided. In some embodiments, the rebalance system includes electrochemical cell and a photochemical cell. In some embodiments, the photochemical cell contains a source of ultraviolet radiation for producing HCl from H2 and Cl2 generated by the system. The HCl product may be collected or circulated back through the system for the rebalancing of electrolytes. A rebalance cell for use in a rebalance system is also provided. In some embodiments, the rebalance cell is the combination of an electrochemical cell and a photochemical cell. In some embodiments, a source of ultraviolet radiation is housed in the cathode compartment of the rebalance cell. In some embodiments, the source of ultraviolet radiation is used to effect the formation of HCl from H2 and Cl2 present in the rebalance cell. The HCl is dissolved in aqueous electrolytes contained in the rebalance cell, which can subsequently be circulated through a rebalance system for the rebalancing of redox cells.