To address the energy demand of the growing world population, the transition from polluting exhaustible energy sources to clean inexhaustible energy sources is imminent. Solar energy is one of the energy sources that has been studied extensively. In particular, the application of solar energy in photoelectrochemical water splitting has gained wide interest in generating hydrogen as renewable fuel. The objective of the research is the elucidation of light scattering mechanism of surface plasmon resonance of silver. Surface plasmon resonance is the phenomenon of collective oscillation of free electrons in noble metals on electromagnetic irradiation. This property of noble metals is valorised in influencing the optical and photoelectrochemical efficiency of photoanodes of interest. In this study, n-type photoanodes, BiVO4 and TiO2 are prepared and functionalized with different sized silver nanoparticles. The influence of size of nanoparticles is investigated with respect to the ability of light scattering using UV-Vis absorption measurement and Incident Photon to Current Conversion efficiency. The difference in optical and photoelectrochemical behaviour imparted by nanoparticle on BiVO4 and TiO2 gives insight about the light scattering mechanism and the need for spectral overlap of silver surface plasmon resonance with the bandgap of the semiconductor.