Maestrale has sold the stake to Produzione Italia, a wholly-owned subsidiary of Swiss energy group Repower. The sales price was not disclosed.
Repower, known until recently as Rätia Energie, has an option to acquire the remaining 61% in the wind farm two years after project commissioning, expected this summer.
The deal is in line with Theolia's "Develop, operate and sell" strategy unveiled last year where the group focuses on developing wind projects until commissioning, then selling the wind farm after two to four years of operations.
The strategy is designed to allow Theolia to benefit from higher visibility on expected cash flows and to increase returns for Theolia shareholders.
Repower already operates the 9.35 MW Corleto Pertica wind farm in the region of Basilicata and is planning to further develop its portfolio of Italian wind projects.
The Giunchetto wind farm is expected to produce roughly 52 GWh of electricity each year and to satisfy the electricity requirements of 26,000 households. It is composed of 35, 850 kW turbines from Danish manufacturer Vestas.