All 15 people aboard the World Bora CTV, owned by Danish shipping company World Marine Offshore, were injured, according to the German Maritime Search and Rescue Association.
Four people were transported to hospitals by helicopter, while 11 were taken to medical centres by ambulance, a spokeswoman added. All of their next-of-kin have been informed, Iberdrola stated.
On board were four crew members, and 11 technicians, nine employed by turbine manufacturer Siemens Gamesa, and two by Iberdrola.
The 30-metre long vessel had collided with the Raba, an 80-metre long cargo ship about 13km from the island of Rügen. No one aboard the Raba was injured.
Crew on board the World Bora had been travelling to the 350MW Wikinger wind farm to carry out "ordinary operation and maintenance activities", Iberdrola stated.
Wikinger consists of 70 turbines and is located 45km north-east of the island of Rügen.
Crew from search and rescue delivered first aid before emergency doctors and paramedics arrived.
Firefighters from the Sassnitz on nearby Rügen Island transported two seriously injured people from the bridge of the CTV to land to make transport via stretcher as smooth as possible, the search and rescue association added.
German maritime police has opened an investigation into the cause of the collision.
An Iberdrola spokesman said: "Although, in principle, none of the injuries seem to be life threatening, Iberdrola is following up on their condition.
"Iberdrola would like to express its gratitude to all the rescue teams involved in the operation for their diligence and professionalism."
World Marine Offshore did not wish to comment.