This paper presents an algorithm for the study, sizing, simulation and data analysis of complete integrated PV/Wind/Hydro-Battery systems. It is a computer program developed for determining and sizing of renewable-based energy system that can be used for electric power supply at any given time. This tool is used in sizing the integrated PV/Wind/Hydro-Battery for sustainable power supply at Nkanu-West local government secretariat. The program calculates the optimum configuration of the system according to the weather data as well as the period of operation of solar cells. From the simulation results, it was shown that the source and load characteristics are effectively sized and the supplied energy is efficiently and rationally utilized. The structural analysis of the program is described in details through data flow diagrams. The proposed sizing tool is validated with HOMER software and the program can be adapted for application in any area.