The deal covers Nordsee One, Two and Three projects, which are located 40km north of Juist Island in German territorial waters.
The €1.2bn, 332MW Nordsee One project, which is in advanced development, will feature 54 wind turbines.
The wind farm, which is planned to be completed by the end of 2017, is estimated to generate more than 1,300 gigawatt hours of electricity per year for about 400,000 households in Germany.
A final investment decision and financial close on Nordsee One project is expected to be reached in the first half of 2015 with in-water construction planned to start in 2016.
Nordsee Two and Nordsee Three projects, which are in early stages of development, have a combined generating capacity of about670MW.
The companies plan to develop both the projects in the next ten years as offshore wind tariffs are extended and the grid infrastructure is made available.
RWE Innogy will retain a 15% equity stake in the three projects, which are located in an area of about 100km².
RWE Innogy chief executive officer Hans Bünting said: "Today’s agreement marks the first important milestone on the way to realize the Nordsee One offshore wind project.
"As part of RWE Innogy’s capital light strategy going forward, we are going to share the capital required for offshore-projects through partnerships."
Northland Power president and chief development officer Sean Durfy said: "We are excited to announce this next stage of Northland’s offshore wind development program.
"The Nordsee One project is well advanced and increases Northland’s offshore wind portfolio to 642 MW {net to Northland}, with further growth potential in subsequent phases."
Image: Nordsee One, 2 & 3 are located 40km north of Juist island in Germany. Photo: Courtesy of RWE Innogy.
