These include the Battery Management System (BMS), Power Conversion System (PCS), and Energy Management System (EMS), often referred to as the "3S System. " Together, they ensure safety, efficiency, and optimal performance. Advanced BMS, such as EVESCO's, monitor cells, modules, strings, and the entire system in real time, using. . Battery Energy Storage Systems (BESS) are pivotal in modern energy landscapes, enabling the storage and dispatch of electricity from renewable sources like solar and wind. As global demand for sustainable energy rises, understanding the key subsystems within BESS becomes crucial. The core technologies are concentrated on battery pack, battery cluster structure design, battery system thermal design, protection technology and battery management system. A common solution is to send excess power back into the grid.