The stake is owned by U.S. buy-out fund KKR and a deal would value X-elio at as much as 2.5 billion euros ($2.68 billion), Expansion reported.
Expansion said KKR had hired investment banks to sell its stake while Brookfield, which first bought a stake in X-elio in 2019, holds a right of first offer.
X-elio operates and builds renewable power infrastructure mainly in Spain, the United States and Latin America.
With its sunny plains, fast-flowing rivers and windy hillsides, Spain is attracting many investors for renewable energy projects.
Brookfield and X-elio did not immediately return messages seeking comment. KKR was not immediately available for comment.
($1 = 0.9341 euros)
(Reporting by Inti Landauro; editing by Jason Neely)