The 150 megawatt portfolio has attracted interest from a range of industrial and financial names with final bids due by the end of next week, the sources said.

Investors have been snapping up renewable power generation assets as the global drive to orientate industrial and financial portfolios away from planet-warming carbon picks up pace.

Last month, Italy's Falck family sold its controlling stake in Falck Renewables at a 30% premium while French utility Engie and a fund owned by Zara founder Amancio Ortega bought solar assets in Spain.

NextEnergy is looking for around 420 million euros for 105 solar plants dotted across Italy including clusters on the islands of Sicily and Sardinia, the sources said.

"There has been considerable interest from private equity," one of the sources said. Danish fund Obton, solar power producer Sonnedix, UK fund Equitix and Italian renewables investor Tages have all expressed an interest, the source added.

The deal is nicknamed Project Telkes, after late Hungarian solar energy researcher Maria Telkes, according to an information document seen by Reuters.

Most of the plants were built under government incentive schemes that guarantee stable returns, the document showed.

NextEnergy, Obton, Sonnedix and Equitix did not immediately reply to emails seeking comment. Rothschild, Intesa Sanpaolo unit IMI and Tages all declined to comment.

($1 = 0.8815 euros)

(Reporting by Isla Binnie and Stephen Jewkes; Editing by Edmund Blair)

By Isla Binnie and Stephen Jewkes