Storing solar energy using a stable visible light absorbing Cs₂AgBiBr₆ double perovskite is achieved using a photoelectrochemical (PEC) device with cobalt complexes and methyl viologen redox mediators. Under illumination, a potential gain of nearly 500 mV is achieved for charging. The charge–discharge cycling was carried out, and using in situ emission and FTIR studies, the self-discharge and solvent crossover were investigated.