Solon SE, Solar Millennium AG and Solarhybrid AG have all declared bankruptcy due to a cocktail of plunging equipment prices, overcapacity and falling government subsidies.
“The executive board has reached the conclusion that a going concern of the company cannot be restored on a sufficiently secure legal basis,” a Q-Cells statement said.
Five years ago, Q-Cells was valued at €8 billion and at one point, it was the world's largest maker of solar cells. But as cheaper competition grew abroad and government subsidies were whittled away at home, its stock fell.
On 2 April, shares in Q-cells were trading at just €0.126, down from a peak of €84 in 2007.
Analysts say that highly-favourable state loans to solar companies in China have contributed to a bottom-line logic of outsourcing solar power equipment production there.
Prices for Chinese solar modules fell by 30%-40% in 2011 alone, while the country's market share grew to 57%. It only manufactured a third of the world’s solar cells in 2008.
When Berlin's generous subsidies to the solar sector were slashed, many German companies were left high and dry.
Separately, solar wholesaler Phoenix Solar said financing talks were taking longer than expected after subsidy cuts forced it to adjust a restructuring plan submitted last December.