Solar energy technologies offer a clean and renewable energy source, and are essential components of a sustainable energy future. The current paper presents a method for technical-economic optimization of an autonomous photovoltaic system. The principal objective of this study is to find the optimum characteristics of a photovoltaic system, able to accomplish the energy requirements of a given load distribution, for a specific site. Mathematical models are exploited to analyze the working of the photovoltaic system. These models present an estimation of the recovered solar energy anywhere and anytime, an evaluation of the electric energy produced by a photovoltaic generator and a determination of the storage unit characteristics. Then, the optimizing step is done based on lack of energy to generate probability (LEGP), percentage of the surplus of energy produced (PSEP) and the cost of the kilowatt-hour produced (C-kWh). A case study has been presented to determine the optimal system configuration used to satisfy the requirements of a typical residential home located in Sfax, Tunisia. (C) 2011 Elsevier Ltd. All rights reserved.