A redox battery energy storage system including multiple energy storage stacks having multiple reactor cells is disclosed. Each of the energy storage stacks may include an integrated DC/DC converter configured to convert an output voltage of the stacks to a higher output voltage. The output of the DC/DC converts may be coupled in parallel to an energy storage system output bus. By configuring the energy storage system in this manner, inefficiencies and losses caused by shunt electrical currents in the systems may be decreased.