Demonstrating single-junction hybrid perovskite functionality in tandem water splitting applications establishes a foundation for exploring various low-cost photoanode-perovskite PV combinations. The sustained photovoltage and photoconversion efficiency of the single-junction CH3NH3PbI3 PV even under low energy excitation enables exceptional performance in tandem light-harvesting assemblies. The operating point of the CoPi/BiVO4−CH3NH3PbI3 PV device is well below the solar-to-electricity conversion efficiency of the underlying perovskite solar cell, stemming from the limited photocurrent density of the BiVO4 photoanode. Therefore, significant opportunities exist for advancing metal oxide photoanode capabilities when used in conjunction with perovskite solar cells. Improving the BiVO4 absorption and light-harvesting efficiency while maintaining limited scattering at longer wavelengths could markedly enhance BiVO4-perovskite PV output. With all other parameters remaining fixed in the CoPi/BiVO4−CH3NH3PbI3 system investigated herein, realizing only ∼60% of the maximum theoretical photocurrent of BiVO4 would yield a STH efficiency over 5%. Alternatively, coupling single-junction perovskite solar cells to lower band gap metal oxides with sufficiently negative flat band potentials could equalize the absorbed photon flux between the two layers, providing better utilization of the full capabilities of the perovskite PV. Replacing CH3NH3 + cations with larger formamidinium ions (HC(NH2)2 + ) opens possibilities for lowering the band gap, bathochromically shifting the absorption onset and enhancing lead halide perovskite functionality as an underlying layer in tandem light harvesting assemblies.