A system for hydrogen production via water electrolysis using solar energy has been designed and is presented in this paper. Investigations were related to the experimental measurements and modeling of the 60W electrolyzer and 100W PV module separately and, subsequently, as coupled system. The goal of this paper was to increase system efficiency while simplifying the system's design. Electrolyzer features related to operating temperature, voltage and electric current were investigated in detail. In the mathematical model of the electrolyzer, important parameters were determined based on UI characteristics, which included the electrolyte ohmic resistance, the electrode overvoltage, and the electrode active surface. Experimentation allowed the authors to improve the mathematical model of the electrolyzer. It clear explains phenomena of variable temperature in real conditions due to the new steady state and higher temperature profile developing as process continues. This statement presents the main contribution of this work. It is supported with experiments and explained in detail through the paper. With efficiency of 77.06% the experimental systems of the electrolyzer and PV module are designed to be roughly compatible with each other. The emphasis is to describe the important parameters in both systems. All mathematical models were programmed in Simulink/MATLAB software. Copyright (c) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.