Due to the integration of hybrid sources, the current power system network is very complex and is being utilized to its full capacity in terms of economic scenario and asset utilization. The stability margin needs to be obtained for improving security and to avoid voltage collapse in the system on a larger scale. The main contribution of the current work relates to the following issues: (i) the proposed cumulative L-Index method has been used estimate the position of distributed generations (DGs) to reduce voltage deviation and increase the voltage stability margin. (ii) The impact of solar PV has been determined by the battery’s voltage stability margin and size. (iii) The optimal battery size with the solar PV and D-STATCOM has been determined. (iv) The total cost consists of fuel cost of DG, energy loss, emission cost of DGs, fixed cost, and operation and maintenance costs have been determined. The VSM has been enhanced by 41.60% with DG installation, as compared without DG. The IEEE-69 bus test system for radial and mesh distribution has been carried out for VSM analysis. The PSO and GAMS optimization has been used for the optimal size and location of the DGs, based on the proposed cumulative L-Index method.