To understand the consequences of choosing one equivalent circuit over the other, the impedance response of a p-Si│a-TiO2│Pt photocathode device was first revisited. Figure (a) shows the currentpotential response of a typical device under 0.1 sun illumination. This light intensity was used to reduce The extracted doping densities and flat-band positions correspond to p-Si. 0.1 sun data taken from Maxwell conversion. Resistances obtained using the e) Voight and f) Maxwell circuit, showing significant differences in obtained results. For voltages positive of 0 V vs RHE a Voight circuit was used, as determined previously. Here, the surface charge transfer resistance is shown in black.