Hydrogen from renewable energy sources is a clean and sustainable option as a fuel and is seen as a potential alternative to gasoline in the future. However, in the near future the use of hydrogen in internal combustion engines is possible at low fraction in mixture with compressed natural gas (HCNG fuel). This paper illustrates a developed method for sizing stand-alone photovoltaic hydrogen system for supplying hydrogen (PV/H-2Fuel) to the HCNG preparation plant. This method is based on a proposed simple system design with two PV arrays. Such designs supply sufficient and separated power to the hydrogen production and compression devices. The method allows a system components sizing for any hydrogen fraction in the HCNG fuel. Case studies are carried out to verify the relevance and effectiveness of this method. Simulation results show that the proposed sizing method provides a good tool to compute the optimal system components' sizes for achieving high energy efficiency with rational system cost. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.