The Fraunhofer IEE developed and tested an innovative pumped hydro storage concept called «StEnSea» (Stored Energy in the Sea). In contrast to well-known conventional pumped-hydro power plants, which use two separated water reservoirs of different heights, the StEnSea concept uses the static pressure of the water column in deep waters. Therefore, a hollow concrete sphere is placed on the sea bead that acts as the lower reservoir. In 2016, the StEnSea concept was successfully tested with a 1:10 scaled prototype in Lake Constance nearby the German town Ueberlingen in a water depth of 100 m.  Currently, a 1:3 scaled prototype is under development. While the concrete sphere is developed and built by external project partners, Fraunhofer IEE is responsible for developing the technical unit (TU) inside the sphere. The TU holds the pump, valves, pipes, sensors, and measurement & control equipment.   Briefly, the main objectives of the master thesis include: Designing the case of the TU Placing of all components, wires, and pipes inside the TU Designing the flange to connect the concrete sphere with the TU Drawing detailed 2D/3D plans of the TU Designing detailed construction directions to assemble the TU with all components