Superconductor cable having a plurality of flat, tape-shaped ribbon superconductor wires assembled to form a stack having a rectangular cross section, the stack having a twist about a longitudinal axis of the stack. Multiple superconductor cables including twisted stacked-cables of the flat-tape-shaped superconductor wires, and power cable comprising the twisted flat-tape stacked cables are disclosed. Superconducting power cable disposed within and separated from an electrical insulator with a space passing cryo-coolant between the superconducting cable and insulator is also disclosed.