Opel’s plea for financial help took a bizarre turn on Wednesday when Solarworld, a German solar energy company, said it was interested in buying the ailing carmakers’ German operations.

In a move that was rebuffed by Opel’s owner, General Motors, Solarworld said it was prepared to inject €1bn into the carmaker’s four German plants and its research and development centre. It added that it planned to turn the GM subsidiary into the first “green” auto company in Europe.