Although business is seasonal, being coupled with turbine installations, WEC Turmbau Emden forecasts "a 40% drop in output over the coming months due to the effects of the tendering system," said Enercon.
A tendering system for allocating support for onshore wind was launched in Germany in spring 2017.
"The order situation for turbine components manufactured in Emden has declined sharply," Enercon told Windpower Monthly.
WEC Turmbau Emden "has to react to the situation" and will shed most of its temporary workers, probably at the end of 2017.
This will affect 120-140 workers, and other contract suppliers will also be hit, Enercon added.
The concrete tower segments are for hybrid towers for 3MW and 4MW class turbines mainly for the German market, Enercon said
Like several other companies exclusively supplying Enercon, WEC Turmbau Emden is a subsidiary of Dutch company Toren Productie.
Blade manufacturer Rotorblattfertigung Magdeburg, which exclusively supplies rotor blades for Enercon's 1MW turbines, will cease operations at the end of 2017, with loss of 140 jobs. It is also owned by a Dutch firm.
After publication of the "Paradise Papers" — leaked files that cast light on how companies and individuals are avoiding tax using artificial structures — the Netherlands is under fire for being a tax haven.
An Oxfam analysis, released in May 2016, of European Commission data showed that out of 33 harmful tax practices listed by the EU executive, 17 were identified in the Netherlands.
Enercon has not yet responded on whether Dutch, rather than German, ownership of WEC Turmbau Emden has fiscal advantages.