Integration of Distributed Generation (DG) increases the intricacy of the distribution feeder. Determining the optimal location of DG with minimized complexity is an important task for distribution engineers. The DG integration requires the evaluation of technical aspects that demands a wide network of vulnerability and operational effects. The test network adopted in this network is modeled as a directed graph network that is formed from a power flow method in Backward-Forward-Sweep algorithm. The topological importance of each node is derived from betweenness centrality to represent the weights. A DG unit is used to supply the real and reactive power. An Optimal Performance Index (OPI) is introduced in this work to combine technical and critical indices, namely real and reactive power loss, voltage deviation, voltage and current harmonic distortion, vulnerability and marginal indices for DG penetration with Vulnerability Index (VI) weightage factor. The VI weightage factor is to determine the degree of criticality of each node when DG is integrated. The OPI evaluation leads to the determination of optimal placement of DG in IEEE 13 radial feeder with constant DG load model. Different case studies have been used that include the OPI evaluation with multiple DG. The results are observed and analyzed to validate the proposed model.