The article presents a genetic algorithm (GA) application to find the best location and reactive power injection of a FACTS device in a power system. The GA is employed to increase the energy efficiency of the system, considering that only the best individuals of a population are selected to create new possible solutions and these are meant to improve the energy efficiency of the system; the node and the reactive power values are considered as the elements needed to maximize the fitness function. Simulations are performed on a 33 bus test power system employing two different Matlab programs to run the power flow and the location of the device. The power flow program performs a voltage limits check. Results show the evolution and the increase of the energy efficiency in the system.