The federal economy ministry outlined the new targets after an agreement was forged between the country's transmission system operators, the federal government and local coastal authorities.
If adopted, the legislation would increase Germany's current 15GW of offshore wind by 2030 target. The country currently has 7.5GW of operational capacity.
The German cabinet approved the amendments on Wednesday (1 June), but the bill would still need to be approved by parliament before it becomes law.
Industry bodies and state governments welcomed the increased ambition, but raised concerns about multi-round tendering processes that could "considerably slow expansion" of the offshore wind fleet.
The German economy ministry has also published a schedule setting milestones to ensure planning and permitting, construction of the cable links to the onshore networks, and building the offshore sites go "hand in hand".
Lower Saxony's energy ministry increasing the target by 5GW was only possible thanks to the use of new 525kV cable technology that doubles transmission capacity compared with standard 320kV technology.
Not all the electricity has to be transmitted, however, stressed Olaf Lies, Lower Saxony's environment and energy minister, who called for steady and consistent expansion of hydrogen usage.
Germany had planned to install 11 new offshore connection systems by 2030 to connect projects to the national grid.
To accommodate the additional 5GW, Germany's network development plan now foresees 14 new connections in 2021-2030: nine in the North Sea and five in the Baltic Sea.
The law - approved by the federal government on Wednesday (3 June) - pegs the expansion for offshore wind in accordance with the country’s current 2030 climate protection programme.
Managing director of the German offshore-wind industry group WAB, Heike Winkler, welcomed the amendments. However, her organisation warned that the new tendering model for offshore wind projects could “considerably slow down the exploitation of Germany’s offshore wind potential at sea”.
The bill proposes initiating additional bidding rounds if more than one entrant request to generate power without subsidy.
WAB has jointly advocated the introduction of contracts for differences as a tendering model for offshore wind projects with the association of German offshore wind farm operators, the BWO.
“The stable investment conditions associated with contracts for differences would strengthen domestic small and medium-sized enterprises, while at the same time relieving the burden on electricity customers,” WAB said.
Winkler added that a national hydrogen strategy is needed before the parliamentary summer break, which would work in parallel to the ongoing legislative process for offshore wind.
Production of green hydrogen, produced using renewable energy, at the coast and later at sea is a significant building block in Germany's clean energy transition, known as the Energiewende.