Incorporating new technologies such as Battery Energy Storage Systems (BESS) and Renewable Distributed Generators (DGs) into power systems provides distinct opportunities and challenges in terms of reliability. This paper analyzes the effect of the system reliability of these technologies using simulations in the ETAP (Electrical Transient Analyzer Program) software. The analysis determines how various types of renewable resources, such as solar and wind, together with BESS, affect system-level reliability metrics such as System Average Interruption Duration Index (SAIDI), System Average Interruption Frequency Index (SAIFI), and Loss of Load Probability (LOLP). Different scenarios of operational configurations of DGs and BESS are simulated to evaluate their contribution toward system reliability enhancement and outage duration minimization. Results underline the effectiveness of renewable DGs and BESS in restoring the system from partial outages by reducing operational losses and improving the reliability of the system. The paper also presents the best approaches for calculating the reliability improvements from optimal resource allocation with respect to resource sizing and placement. These approaches will aid utilities and system engineers in the planning and design of modern power systems with high levels of renewable energy sources and energy storage systems.