Due to the increasing interest on renewable sources in recent times, the studies on integration of distributed generation to the power grid have rapidly increased. Distributed generations (DGs) play an important role in distribution networks. Among many of their merits, loss reduction and voltage profile improvement can be the salient specifications of Distributed generations (DG). Non-optimal locations and non-optimal sizes of Distributed generations (DG) units may lead to increase losses, together with bad effect on voltage profile. Proper location of Distributed generations (DGs) in power systems is important for obtaining their maximum potential benefits. Distributed generation (DG) units reduce electric power losses and hence improve reliability and voltage profile. Determination of appropriate size and location of Distributed generation (DG) is important to maximize overall system efficiency