ESS (Energy Storage System) : refers to a system used to store electrical energy and release it when needed. In a broad sense, it can include mechanical energy storage (such as pumped storage), thermal energy storage, electrochemical energy storage, etc.
BESS (Battery Energy Storage System) : A type of ESS, specifically referring to a system that uses “battery” as the energy storage medium, usually composed of batteries, battery management system (BMS), power conversion system (PCS), energy management system (EMS), etc.
Battery Storage : Battery energy storage is usually a popular name for BESS, used to describe the ability and method of storing electrical energy through batteries.