The so-called breathing cap, is being proposed by the federal economy ministry as part of the Renewable Energy Act reform.
Support cuts are planned alongside making the marketing of wind generation in the wholesale market obligatory. The market price is to be topped up with a wind premium.
An overly harsh reduction of support will make wind developments uneconomic and stop expansion throughout Germany, warned German wind energy association BWE today.
The "breathing cap" is unsuitable for wind energy due to the long project development periods and high preliminary investments, it said. Without knowing the support level, developers will not know whether their projects will be economically viable.
Offshore wind is faced with a fixed 6.5GW to 2020 and another 15GW, or about two wind projects per year, to 2030, the paper confirmed.
The amended Renewable Energy Act is due to take effect on 1 August 2014, according to a economy ministry "cornerstone" paper, due for discussion by the government later this week.
In an attempt to prevent a last-minute rush on installations before support cuts kick in, only those projects that have a full permit on 22 January 2014 and wil be commissioned before the end of 2014 will be eligible for support under current rules, the paper stated.