This paper illustrates analyzing the feasibility of developing solar power system in existing educational building by converting it from electric energy to solar energy. This study depending on the fact that educational building has a lot of free spaces that could be used especially that Egypt is enjoying average sunshine hours between 6-12 daily so the development potentials of Solar Energy appear very obvious adding to that the relatively higher cost of fossil energy and its bad impact on the environment. Three methods were combined to ascertain building properties and determine which place were the most suitable for BAPV installations which are analysis study, physical simulation and empirical study The methodology is then tested by applying the steps on the building. Then a cost analysis had been performed to give actual values for the amount of money saved by retrofitting and installing BAPV systems. Energy simulation program –Design Builderwas used to analyze the energy performance of the case study building and compare it to the retrofitted case to show the amount of electricity saved.