摘要： This present research paper aims at showing the active role of the building equipped with photovoltaic (PV) plant in terms of energy, economy, and ecology and its impact on the development of society. Since the installation of PV plants on buildings is a rarely used technology in Algeria, we intend to conceive 30 kWp medium power plants on pilot administrative buildings, which will be generalized to two other buildings of the same type, connected to urban electricity network so as to reduce the consumption of electricity which costs much money to the local authorities, the pilot site is located in the town of EL-ATTAF, in the northwestern of Algeria. It is Mediterranean climate with average radiation of 5.14 kWh/m2/day and average yearly temperature of 19.4°C. The study highlights the technical and financial feasibility of the system based on a simulation with Homer which estimates a load of 41610kWh/year, energy production of 47872 kWh/year, an optimal angle of inclination of 32°, saving of 454 m3/year of natural gas and avoiding huge quantities of pollutants (CO2: 549 kg/year; SO2: 9.6 g/year; NOx: 0.5 kg/year).