One of the basic obstacles in the deployment of the clean technologies such as wind turbines or PV modules is their intermittent nature due to dependency to the wind speed and solar radiance. The authors in this paper aim to analyze the effect of the clean technologies such as wind turbines and PV modules in the total and individual costs of the distribution system. In order to model the uncertain nature of the clean technologies, a probabilistic method is proposed in this study. So, a DG planning problem based on the hourly variations in the wind speed and solar radiance in order to reduce the total cost of the distribution system is proposed. The hourly variations of the load as well as the hourly variations in the wind speed and solar radiance is considered. All of the defined economic, technical and environmental functions are turned into cost functions. An encouraging and punishment mechanism is defined beside the other cost functions. The planning problem is formulated as mixed integer nonlinear programming problem (MINLP). The proposed method is applied on the 9-bus distribution system and the results show a significant reduction in annual costs of the distribution system in presence of the DG units.