A Battery Energy Storage System (BESS) is a technology that stores electrical energy in rechargeable batteries for later use. It plays a vital role in modern power systems by balancing electricity supply and demand, improving grid stability, and enhancing energy reliability. BESS is widely integrated with renewable energy sources such as solar and wind to store excess energy and deliver it when generation is low. It also helps reduce peak electricity demand, lowers energy costs, and provides backup power during outages. As the transition to clean energy accelerates, BESS has become a key solution for creating a more efficient, resilient, and sustainable electrical grid.