In this paper, a study on the transient stability of power system with a large amount of solar photovoltaic (PV) penetration was performed on the famous 30 bus IEEE test system, under the Power System Analysis Toolbox (PSAT) simulation software. Based on the critical clearing time (CCT) as a stability index. The simulation results showed a significant decrease in network stability performance after solar PV penetration, this degradation of the power system stability is due to the non-participation of photovoltaic sources in the regulation of the voltage plan as a consequence of the absence of reactive power, which leads us to have recourse to the FACTS systems. the simulation results after integration of the two famous types of FACTS (SVC, STATCOM) clearly showed the improvement of network stability with a slight superiority in favor of STATCOM.