Hydrogen as an energy currency, carrier and storage medium can contribute to solve the problem of intermittent availability of renewable energies. In this paper, we study the production of hydrogen by a proton exchange membrane (PEM) electrolyzes (WE) using photovoltaic energy (PV) as source of electricity. Experiments were performed to model and optimize the direct-coupling system. Mathematical and empirical models based on experiments were used to simulate the system. RMSE was about 2% for the PV and WE. Optimization of direct connection was carried out to improve the system efficiency. However, it was noticed that the simulation of the system does not fit well the experimental results. Nevertheless, the RMSE is about 7%. In this study, we emphasize the need to develop appropriate models for hydrogen production system that operates in direct connection mode. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.