In this study, an experimental setup is designed and constructed to investigate the effects of varying solar light intensity on the PV (photovoltaic) cell efficiency and the performance of photo-electrochemical (PEC) based hydrogen production. In the experimental setup, the solar light is split to be utilized by PV module for electricity production and by photo-electrochemical reactor for hydrogen production, and the sunlight is concentrated using Fresnel lens. Furthermore, the losses caused by transmittance and reflectance of the materials within the system are determined. The efficiencies for each light conversion process are calculated together with the overall efficiency and comparatively assessed for concentrated and non-concentrated light conditions. The characterization results of the solar PV module show an increase in total power output and efficiency from non concentrated to concentrated conditions, corresponding to 12% to 16%, respectively, while only a higher wavelength spectrum is exposed to PV surface. The energy efficiency of light conversion from concentrated light to PEC reactor is obtained to be 49.3%. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.