RWE hopes it can overcome a crisis at its British unit by 2018, after the business swung to an operating loss in the past financial year, its chief executive said.
"What happened there (in Britain) was a disaster," Peter Terium said in a speech, pointing to a rapid loss of customers and billing issues that drove Npower into the red.
"We hope to be out of the valley of tears in the U.K. by 2018."
RWE also confirmed that 2,400 jobs would be cut from Npower, but Bernhard Günther, RWE's CFO, said a sale was not on the table.
"We are confident that the job cuts will take us where we want to be, back to normal profits in 2018 again," Günther told CNBC.
"We had to hire additional people in order to fix up our invoicing and billing problems and as we get our systems and processes back under control, we no longer need these additional head count."
Günther also talked about the difficulties of doing business in the U.K. market.
"All of the big players in the U.K. retail market are suffering from severe competition from new entrants who benefit from the constantly falling power prices," he said.
--Reuters contributed to this report