This research aims at studying types of PV Systems and their applications in many practical fields. It also aims at looking into all the components and technical specifications of the equipment. That's what serves these systems' design and implementation ways through designing and performing a 12 [KW] Stand- alone PV System. This system is usually used to supply one of the Green Buildings lighting at night with a back- up grid to achieve a high reliability in supplying the load. This project also aims at strengthening national qualifications in the fields of research, development and operation.