Germany’s clean-energy industry said government plans to accelerate cuts in aid to operators of wind and solar-power plants threaten to derail the country’s transition to renewable sources.

Wind-turbine maker Nordex SE, which has benefited from booming installations on land, fell the most in more than a month in Frankfurt trading after weekend reports that Economy and Energy Minister Sigmar Gabriel aims to rein in subsidies. German utilities RWE AG and EON SE welcomed Gabriel’s plans.

Proposals to reduce aid for new onshore wind units by as much as 20 percent in 2015 from last year's levels are “counterproductive,” the BWE wind lobby said. Excessively harsh cuts “threaten the wind energy expansion all over Germany” and so risk “derailing the energy switch,” Sylvia Pilarsky-Grosch, BWE's head, said in an emailed statement.

Chancellor Angela Merkel's government intends to cut the cost of her plan to shutter Germany's nuclear plants and move Europe's biggest economy toward renewables. She says the top priority of her third-term government, which took office last month, is to modernize the system of clean-energy aid after rising wind and solar costs helped send consumer power bills soaring. German household electricity costs are the second highest in the 28-nation European Union.

Coalition meeting

Gabriel, who assumed overall control of the biggest energy overhaul of any developed country, seeks to limit subsidies paid to operators of land-based wind turbines to no more than 9 euro cents a kilowatt-hour in 2015 and reduce the expansion to about 2,500 megawatts a year, according to a ministry document prepared for a meeting of Merkel’s coalition on Jan. 22-23. Developers will get the current aid if their units are authorized before Jan. 22 and enter operation this year.

An allied proposal to charge developers of solar plants who use the power themselves would deter investors and stop ordinary Germans from taking part in the energy switch, the BSW-Solar lobby said in an open letter to the chancellor.

“While the U.S., Japan and China invest massively in solar energy, the German photovoltaic market has more than halved as a result of aid cuts that are too speedy,” BSW-Solar said in the letter, emailed today.

The government also plans to reduce the target of expanding solar panels to 2,500 megawatts a year, from 2,500 megawatts to 3,500 megawatts currently, and limit new biomass units to 100 megawatts a year, according to the document. Der Spiegel magazine reported its contents two days ago.

Shares slump

Nordex shares slumped 5.7 percent to 10.91 euros, the steepest one-day plunge since Dec. 12.

“We welcome the fact Mr. Gabriel is addressing the matter so soon,” Annett Urbaczka, a spokeswoman at RWE, Germany’s second-biggest utility, said by phone from Essen. She declined to comment on the details of Gabriel’s proposals.

They carry the potential to “reduce the cost when expanding renewables,” Carsten Thomsen-Bendixen, a spokesman for EON, the biggest utility, said today by phone. “That’s good news for electricity consumers.”

Merkel’s cabinet will vote on a draft bill April 9, Gabriel told reporters today in Berlin. The law is to take effect Aug. 1.

— With assistance from Brian Parkin in Berlin and Tino Andresen in Dusseldorf.