When Siemens announced a deal to merge its wind-power business with rival Gamesa in 2017, executives saw only upside.
Yet the industry has proved as fickle as the wind.
Siemens warned this week that it was facing a £3.9billion loss this year as a result of issues within its wind-turbine division.
Wrinkles in rotor blades and faulty gears are among the problems uncovered, which have led to operating issues and warranty claims from buyers.
Inflation has only added to headaches.
The Telegraph says the admissions of failures wiped billions off the value of Siemens.
Wind-power market
The German industrial powerhouse has been in the wind-power market for almost two decades and Gamesa, which was until last year a joint venture, traces its roots in the industry back to the 1970s.
Yet a rapid expansion of its manufacturing in recent years has left the combined business over-extended.
Jochen Eickholt, chief executive of Siemens Gamesa, admitted: "We sold turbines too quickly", describing the company as a "victim of our own ambitions".
Siemens Gamesa manufactures blades for wind turbines, which are made up of many layers of material.
The technology must be highly precise.
Mr Eickholt has put the issues down to "wrinkles" within layers of the blades and has blamed suppliers. Some have been cut off in response.
New turbines
Hiccups weren't picked up earlier because the company was focused on the rapid introduction of new turbines and the ramping up of capacity, Siemens Energy chief executive Christian Bruch said.
Kathryn Porter, an independent analyst at energy consultancy Watt Logic, said: "There's been pressure from the developers to have bigger turbines, because then obviously it's easier to build, but there have been a lot of warranty problems.
"Now you're getting people saying behind the scenes - maybe we need to have a pause on this bigger and bigger turbine thing because they just keep breaking."
Profitability has been weak in the industry for a long time, she said.
Problems at Siemens' turbine business are not new.
Tougher market
Issues have been focused within its onshore wind turbine business, which is a tougher market than offshore.
However, worryingly, new issues are still being uncovered.
Siemens Energy has put its entire wind division, Siemens Gamesa, under review despite only recently taking full control.
The review will look at "all options", Mr Bruch said when asked whether parts could be sold. An update is expected in November.
Yet as problems mount, Mr Bruch is still optimistic. "We believe more than ever in the potential of wind power," he told reporters.
FTSE 100
The UK's top share index, the FTSE 100, was up 34 points at 7,561 shortly after opening this morning, following yesterday's 27-point fall.
Brent crude futures were down 0.08% at $86.11 a barrel.
Companies reporting today
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