Serbia’s 66 MW Kostolac wind farm remains offline despite completion of construction, with unresolved issues between state-owned utility EPS and turbine supplier Siemens Gamesa delaying the formal handover and start of commercial operation. The project is valued at EUR 145 million. All 20 turbines have been installed and connected to the grid, and electricity has been generated during trial operations. Regular commercial operation has not yet begun, almost two years after the original completion target of October 2024.
Taking-Over Certificate and dispute over contractual obligations
In June, EPS said Siemens Gamesa had not fulfilled all contractual obligations, prompting the utility to decline signing the Taking-Over Certificate. A joint statement released the following month said the project engineer issued the certificate on 6 March 2026, confirming that construction and installation works were completed. The companies said they would continue working together to resolve remaining issues .
The wind farm’s trial operation started in November 2025, with all 20 turbines connected by the end of that year. By 22 February 2026, Kostolac delivered 37.37 GWh of electricity to the grid before generation was suspended. No date has been announced for the plant’s return to operation.
Expected output and financing under international support
Once fully operational, Kostolac is expected to generate about 115 GWh of electricity annually. That level of output is described as sufficient to cover consumption equivalent to around 30,000 households. The project is also cited as part of Serbia’s efforts to expand renewable generation and diversify a power system still heavily dependent on coal.
The project was financed primarily through international development support. KfW provided EUR 110 million in loans and a EUR 1.8 million grant, while the European Union contributed EUR 31 million via the Western Balkans Investment Framework. EPS added an additional EUR 2.2 million.
Status remains unclear amid undisclosed shutdown reasons
The EU said its contribution had been fully disbursed by March after issuance of the certificate by the FIDIC project engineer . The EU contribution is linked to Kostolac being one of Serbia’s major publicly supported renewable-energy projects.
The precise reasons for the continued shutdown remain unclear. Unconfirmed reports have pointed to additional maintenance payments as a potential factor, but EPS, Siemens Gamesa and Serbia’s Energy Ministry have not publicly disclosed detailed information about outstanding contractual issues.
Kostolac remains an example of a gap between technical completion and commercial operation. Although turbines are installed, connected and able to produce electricity, unresolved contractual and operational matters continue to prevent regular service from starting.
