RWE's Innogy doubles stake in solar specialist before IPO

FRANKFURT, Sept 21 (Reuters) - Innogy, the renewable, networks and retail unit that German utility RWE will list next month, has doubled its stake in Heliatek, a maker of organic solar cells, becoming its largest shareholder, it said on Wednesday.

By participating in an 80 million euro ($89 million) funding round, Innogy raised its stake in Heliatek to 20 percent, from 9 percent, as the group seeks to increase its foothold in the area of solar power.

German chemicals maker BASF, French bank BNP Paribas, French utility Engie and venture capital firm Wellington Partners also took part in the financing, Innogy said.

Aqton, a vehicle controlled by BMW shareholder Stefan Quandt, also took part, Innogy said.

Founded in 2006, Heliatek specialises in super-light and flexible solar films that can be attached to glass surfaces and building facades. It employs 85 staff. ($1 = 0.8971 euros) (Reporting by Christoph Steitz; Editing by Adrian Croft)