A containerized battery energy storage system comprising: a) a standard ISO container comprising a floor and having frames that are separated from each other in a horizontal direction, each of the frames comprising battery modules that are stacked in a vertical direction, b) a fire suppression system (200, 300, 400) including: i) a pipe system comprising a plurality of vertically extending pipes, that are spaced from each other in the horizontal direction, and further comprising a horizontally extending pipe that communicates the plurality of vertically extending pipes with each other, each of the vertically extending pipes being provided between a respective two of the frames and supplying suppressant to at least one of the battery modules of each of the respective two of the frames via slots of the vertically extending pipe,; ii) a plurality of tanks (353A, 353B, 353C) placed under the floor and distinct from the floor or a plurality of tanks having top surfaces, the top surfaces being portions of the floor, the tanks being interconnected in such a way that any single pump has access to the suppressant in all of the tanks, and the tanks being connected to the pipe system and storing the suppressant; the tanks being connected to drains within the floor of the container, that allow suppressant supplied by the vertically extending pipes to return to the tanks and iii) at least one pump (356A, 356B, 356C) being connected via a tube to at least one vertically extending pipe or connected to the horizontally extending pipe via a connection pipe, thereby recirculating the suppressant, supplied by the slots of each of the vertically extending pipes of the pipe system, to the pipe system or a tank of the plurality of tanks (353A, 353B, 353C). a) a standard ISO container comprising a floor and having frames that are separated from each other in a horizontal direction, each of the frames comprising battery modules that are stacked in a vertical direction, b) a fire suppression system (200, 300, 400) including: i) a pipe system comprising a plurality of vertically extending pipes, that are spaced from each other in the horizontal direction, and further comprising a horizontally extending pipe that communicates the plurality of vertically extending pipes with each other, each of the vertically extending pipes being provided between a respective two of the frames and supplying suppressant to at least one of the battery modules of each of the respective two of the frames via slots of the vertically extending pipe,; ii) a plurality of tanks (353A, 353B, 353C) placed under the floor and distinct from the floor or a plurality of tanks having top surfaces, the top surfaces being portions of the floor, the tanks being interconnected in such a way that any single pump has access to the suppressant in all of the tanks, and the tanks being connected to the pipe system and storing the suppressant; the tanks being connected to drains within the floor of the container, that allow suppressant supplied by the vertically extending pipes to return to the tanks and iii) at least one pump (356A, 356B, 356C) being connected via a tube to at least one vertically extending pipe or connected to the horizontally extending pipe via a connection pipe, thereby recirculating the suppressant, supplied by the slots of each of the vertically extending pipes of the pipe system, to the pipe system or a tank of the plurality of tanks (353A, 353B, 353C). i) a pipe system comprising a plurality of vertically extending pipes, that are spaced from each other in the horizontal direction, and further comprising a horizontally extending pipe that communicates the plurality of vertically extending pipes with each other, each of the vertically extending pipes being provided between a respective two of the frames and supplying suppressant to at least one of the battery modules of each of the respective two of the frames via slots of the vertically extending pipe,; ii) a plurality of tanks (353A, 353B, 353C) placed under the floor and distinct from the floor or a plurality of tanks having top surfaces, the top surfaces being portions of the floor, the tanks being interconnected in such a way that any single pump has access to the suppressant in all of the tanks, and the tanks being connected to the pipe system and storing the suppressant; the tanks being connected to drains within the floor of the container, that allow suppressant supplied by the vertically extending pipes to return to the tanks and iii) at least one pump (356A, 356B, 356C) being connected via a tube to at least one vertically extending pipe or connected to the horizontally extending pipe via a connection pipe, thereby recirculating the suppressant, supplied by the slots of each of the vertically extending pipes of the pipe system, to the pipe system or a tank of the plurality of tanks (353A, 353B, 353C).