Onshore and offshore wind farms in Germany generated almost 15 terrawatt-hours of electricity in December, according to the energy and water industry trade association BDEW.
This would be enough to cover the electricity consumption of Berlin or Schleswig-Holstein for one year, it said.
However, in reality there is a lack of energy storage facilities to use volatile renewable power as needed, BDEW added.
The association also said there is a need for grid expansion – particularly to transport electricity from production centres in the north of the country to areas of demand in the south.