Spain's Repsol is struggling to find buyers for a minority stake in its new renewable energy arm, with investors wary of the size and structure of a deal that would limit their say in key decisions, three sources familiar with the matter told Reuters.

Repsol is selling roughly 25% of its low-carbon business which operates wind, solar and hydro plants in Spain, the United States and Chile, and has asked for indicative bids next week, the sources said on condition of anonymity.

Some investors have lost interest due to Repsol's plans to list the company in the next few years, a route which Italian oil and gas firm Eni has chosen for its own low-carbon and client business later this year. 

Investments in listed firms are subject to swings in market value, which discourages some funds, the sources said.

One source said Repsol's advising bank JPMorgan had called some potential investors as many as three times to try to make the case.

JPMorgan and Repsol declined to comment.

Repsol and larger peers BP, Total and Shell need to invest more in renewable generation and other technology to fulfil promises they have made to increasingly climate-conscious shareholders to slash the carbon emissions that contribute to planetary warming.

Repsol boss Josu Jon Imaz first floated the idea of spinning off the unit to raise funds in late 2020.

But after months of talks, many potential investors have been put off by the seller's valuation of the unit, which went as high as 4 billion euros ($4.5 billion), the sources said.

Investors' are looking at valuations closer to 3 billion euros, one of the sources said.

The size of the stake being sold has also become a sticking point as Repsol initially signalled interest in selling up to 49% of the business, but subsequently reduced that to 25%, the sources said.

Further complicating the process, Repsol is planning to clinch separate deals to raise cash for individual assets in the low-carbon business, including a solar site in western Spain.

One of the sources said this made it harder to understand what exactly was covered in the stake sale.

"The impression is that Repsol is offering as little as possible," one of the sources said.

($1 = 0.8844 euros)

(Reporting by Isla Binnie and Andres Gonzalez Editing by Pamela Barbaglia and Mark Potter) ((; +39 06 8522 4392; Reuters Messaging: