In accordance with the present disclosure, a scalable and modular rack-level power infrastructure is described. The power infrastructure may include a power distribution unit (PDU), which receives alternating current (AC) power from an external power source. The PDU may be coupled to a busbar and output DC power to the busbar. The busbar may be coupled to a server within a rack-server system and provide DC power to the server. Additionally, the infrastructure may include a battery back-up unit (BBU) element coupled to the busbar. The BBU element may charge from and discharge to the busbar.