The question was, how to upgrade an existing green roof with a solar system. Most of the existing solar-green roof systems require a full build-up starting from the waterproofing layer. The ND Solar Green Roof Mounting System can be used on new but also existing buildings. This allowed to re-use the existing green roof system (drainage and substrate) and only the vegetation needs to be replaced by vegetation suitable for solar green roofs. By using vegetation blankets instead of sprouts or plug-plants, the roof is green and ready right away after installation. After finalization does the system deliver a gross power output of 7 kWP. We aimed to place a solar system on top of the existing green roof. The ND Mounting System is a Solution, which can be used for new installations and also installations on an existing green roof. The installation only required us to remove the substrate by shifting it temporarily on one side of the roof (NOTE: Make sure that the roof is suitable to cope with the load) and check the existing drainage for full functionality. Once this was done, the system was installed, substrate as ballast have been applied, vegetation blankets have been placed and solar system has been mounted.