AEI will retain a two-thirds stake in the unit, which holds renewable energy assets comprising 2.3GW in 14 countries outside Spain, including the US, Mexico, Australia, Italy, Portugal and South Africa.
The alliance between KKR and Acciona also includes a management agreement under which Acciona will operate AEI’s assets for 20 years for an annual fee.
AEI will have a right of first offer on future renewable energy projects it develops within its operational territory.
Acciona Energía’s pipeline of around 3GW can be accelerated through the partnership.
KKR co-chairman and co-CEO Henry Kravis said: "This investment adds to our track record of building successful partnerships with corporates and families. I am really optimistic about the opportunity to partner with such a prominent renewable energy company and to help further develop what is already one of the largest operating renewable portfolios in the world."
Acciona chairman and CEO José Manuel Entrecanales Domecq said: "The alliance between KKR and ACCIONA marks a new milestone for the renewable energy industry.
"With KKR as a long-term financial partner, ACCIONA is in a strong position to take advantage of the huge opportunities that lie in the global market for renewable energy."
