Energy systems around the world are going through a phase of rapid change. In the UK, smaller scale, decentralised technologies associated with solar, wind, storage, sensors and control systems are developing at a much more rapid pace than larger scale infrastructure. There are also considerable market opportunities associated with the transition. Energy storage plays a crucial role but it is still expensive. There is an urgent need to develop advanced technologies to better model and control battery storage in a smart local energy system. A digital twin is a digital replica of a physical system. This project will develop digital twins for battery storage used in smart local energy systems. The digital twins will improve situational awareness of the energy control system, and enable and facilitate optimal operation of both battery storage units and the local energy systems