In recent decades, the rapid rise in electricity demand has obligated transmission and distribution systems to perform at their maximum capacity. Photovoltaic (PV) system is widely used to meet the increased claim for electrical power. The grid connected PV system has emerged with its simplicity, reliability and insurability, but it pretence limitations in maintaining power quality and steadiness of the power system network. On the other hand due to some restrictions in the construction of transmission lines, there is a possibility of generating block in new transmission lines which results in the blackout of the system. To avoid such critical conditions researchers originate devices to increase the power flow capacity of existing systems, this paper presents a review on Flexible Alternating Current Transmission System (FACTS) devices and its applications. FACTS devices minimizes active power losses while succeeding reactive power flows to keep the voltages within their respective limits.