The self-consumption is a hot topic, it relates to both the energy management and the control of energy expenses and also produce renewable energy. However, the self-consumption present constraints related to variations in the solar production and the load curve of the consumer. In order to promote the use of renewable energies, contribute to the reduction of gas CO2 emissions, protect the environment and ensure sustainable development, FSTS has chosen to install a photovoltaic system in self-consumption. The aim of this work is to present an approach and strategy to find the optimal power of a PV station, adapted to the energy needs of the FSTS, generating the most producible and less spending. A technical-financial study show the feasibility of installing a PV station of optimal power of 200 kWp with a return on investment of 8 and a half years, and a surplus of 30% of solar energy produced annually, the management of this surplus could further reduce the point of profitability of this project.