Guided by the "dual carbon" goals

building energy systems are evolving towards cleanliness

direct current (DC)

and flexibility. As the core form of the new generation of building energy systems

photovoltaic-energy storage-direct current-flexibility system promotes efficient

low-carbon

and intelligent operation of buildings through the deep coupling of photovoltaics

energy storage

DC distribution

and flexibility loads. This paper focuses on the Tongzhou Building in Shanghai

conducting research on key technologies such as photovoltaic system selection and design

energy storage system configuration and coordination strategy

DC distribution architecture optimization

and flexible control system integration. It achieves the coordinated linkage between renewable energy and efficient equipment. Through techno-economic analysis and multi-objective optimization methods

a multi-energy coupling solution and coordinated operation strategy tailored for practical engineering are proposed

providing a replicable and scalable technology integration demonstration and decision-making support framework for similar buildings.