In this study we explore the photoelectrochemical behavior of planar heterostructured FTO/CuBi2O4/BiVO4 electrode and tandem FTO/ BiVO4 || FTO/CuBi2O4 photoelectrochemical cell in order to evaluate the mechanisms of charge separation and transfer in both systems. Both heterostructured and individual electrodes were characterized by SEM, XRD, XPS, and Kelvin probe methods to confirm a successful formation of planar heterostructure. Evaluation of the band gap, conduction and valence bands energy level positions as well as position of the Fermi level of individual components of heterostructure infers the formation of type II heterostructure with an ability to realize both conventional mechanism and Z-scheme mechanism of charge separation. It was demonstrated that photoelectrochemical behavior of both heterostructured electrode and tandem photoelectrochemical cell depends on photoexcitation conditions. Particularly, photoexcitation of either both components in heterostructured electrode or both photoanode and photocathode in tandem cell leads to dominating realization of Z-scheme mechanism of charge separation and transfer.