Most developing countries in the world have witnessed unavoidable increasing power demand. This phenomenon can lead to high power losses and increase in temperature of the transmission lines. Moreover, the continuous increment of the demand can cause reduction of the voltage profile and affect the system stability, which can lead to failure of the power system network due to the stressed condition. Currently, the renewable energy is gaining attention around the globe to meet the generation expansion capacity and to match the increasing load demand. Moreover, the impacts of the renewable energy integration should be studied carefully to avoid any unwanted issues that may lead to power system instability. In this paper, optimal placement and sizing of distributed-generation photovoltaic (DGPV) system are formulated in order to minimize the losses using Adaptive Evolutionary Programming (AEP) on IEEE-30 bus system. DGPV sizes and loadability of selected buses are varied and transmission losses are recorded. The results indicate that the integration of multi DGPV unit in the transmission line improves the line losses of the system.