The penetration of distributed generation (DG) has led to the development of smart grids that incorporate Renewable Energy Sources (RES), thus improving the reliability of Distribution Networks (DN). The stability of such networks can be further increased by integrating Energy Storage Systems (ESSs), a promising technology that can reduce environmental impact. This paper presents an effective method for designing ESS units to enhance distribution system performance. One of these benefits is the ability to increase system reliability through efficient islanding operations. This work proposes an approach to improving system reliability in distribution networks at minimal cost by allocating energy storage systems to avoid blackouts in power systems in the presence of RES (wind turbines). The willingness of consumers to pay to prevent power outages serves as a proxy for reliability value, which optimises the cost of installing the energy storage system. The main objective of this study will be to identify the most appropriate combination of storage units to be installed and loads to be shed to address all conceivable scenarios successfully. Therefore, a probabilistic method that will be used is the genetic algorithm (GA), which considers the stochastic nature of the system components.