This paper presents an upcoming method searching for an optimal placement of phasor measurement units (PMUs) for power system state estimation. The proposed technique is based on phasor technology that allows to estimate the current status of the electrical network in a reliable and accurate way. In fact, looking for full system observability must take into account the lack of availability of appropriate data in all network nodes as well as the intervention of all renewable energy (RE) sources. Other investigations of FACTS systems are extended to enhance smart grid performances and its stability. Experimentally, the application of efficient placement strategies will help to allocate PMUs critically in a 5-bus test system.