The two projects are BorWin1 and BorWin2, which will connect around 1.2GW of offshore projects including the Veja Mate and Global Tech 1 wind farms with a combined capacity of 800MW and located 125km north-west of the island of Borkum.
TenneT will continue to own a majority share and operate the connections.
Mel Kroon, CEO of TenneT, said: "Currently we are working on nine projects to connect wind farms in the German North Sea. These projects total to 5GW of renewable electricity, enough energy to supply 5 million households."
The investment follows the launch late-2011 of Mitsubishi's first offshore turbine, a 7MW direct drive machine.