LISBON, Dec 21 (Reuters) - A unit of U.S. private equity fund KKR announced on Thursday a full takeover bid for Portuguese renewable energy company Greenvolt that values the firm at 1.16 billion euros, after signing agreements to secure a controlling stake.

Gamma Lux said in a statement it was offering 8.3 euros per Greenvolt share, 11.5% above Wednesday's closing price of 7.45 euros and a premium of 32.1% to the weighted average price over the last six months.

After a brief suspension from trading, Greenvolt shares jumped as much as 11% to 8.28 euros on Euronext Lisbon before paring gains to stand 9.3% higher at 8.15 euros by 1215 GMT.

"The acquisition price is 5.7% above our target price, so we would recommend taking part in the takeover bid," Renta 4 analyst Eduardo Imedio said in a research note.

The fund said that it had already signed contracts to buy a total stake of 60.86% in Greenvolt from seven shareholders.

When the fund secures the stake, the offer for the remaining shares - currently voluntary - will become mandatory.

Luxembourg-based Gamma Lux expects the acquisition to complete after May 31, as it is subject to approval by regulators including the Portuguese Competition Authority and counterparts in Romania, Ireland, Britain and Germany.

Greenvolt, which made its market debut in July 2021 after an intial public offering at 4.25 euros a share, has more than 139 million outstanding shares.

The company produces energy and develops biomass, wind and solar projects in Portugal, 15 European markets and the United States.

Renewable energy companies in Portugal and Spain, where there is abundant wind and sunlight, are increasingly popular with investors as governments and corporations shift away from fossil fuels to address climate change.

In the first nine months of this year, Greenvolt's consolidated net profit fell 64.7% to 5.9 million euros from a year earlier even as revenue grew 46% to 268 million euros.

Earnings before interest, taxes, depreciation and amortization (EBITDA) fell 3.3% to 76.9 million euros. (Reporting by Sergio Goncalves, editing by Andrei Khalip, Kirsten Donovan)