A modular locomotive UC storage system includes: at least one cabinet section in a locomotive; a plurality of vertical stacks of UC modules housed within each cabinet section, each UC module including a plurality of UC cells; wherein each UC module within each of the vertical stacks of UC modules is connected in parallel to the UC modules within the vertical stack; wherein each of the vertical stacks of UC modules are connected in series with the other vertical stacks of UC modules within each cabinet section; wherein the connections between the UC modules and between the vertical stacks of UC modules are made by bus bars located such that the UC modules electrically connect with the bus bars in an appropriate combination of series and parallel connections when the UC modules are located in position within the cabinet sections.