Slovenia’s largest solar power plant has entered trial operation near Trbovlje, marking another step in the transformation of the country’s former coal-producing regions towards renewable energy.
The Prapretno complex consists of three units and includes 17,946 solar modules. Once fully operational, it is expected to generate around 10.2 gigawatt-hours of electricity annually. The first part of the facility has been operating since 2022, while the latest expansion brings the project to its planned capacity.
A key feature of the project is its 7 MW battery, which can store up to 14 MWh of electricity. The system is designed to improve the flexibility of the solar plant’s output and provide additional support for the stability of Slovenia’s electricity grid. HSE said initial tests showed that the battery was operating reliably and, in some areas, exceeding its planned technical parameters.
The solar plant is connected to a transformer substation built in 2022 specifically with the future expansion of the facility in mind. Once the remaining procedures are completed and an operating permit is obtained, the entire complex will be remotely controlled from HSE’s control centre.
Prapretno also has a wider significance for the Zasavje region because the solar facility was built on land previously used for waste disposal by the Trbovlje coal-fired power plant. The project therefore forms part of efforts to repurpose former coal-related sites for renewable energy production as Slovenia moves away from its traditional reliance on coal.
The project received €3 million from the European Union’s Just Transition Fund, which supports regions undergoing the economic and energy transition away from fossil fuels. At the opening ceremony, Infrastructure and Energy Minister Jernej Vrtovec described Prapretno as an example of the energy transformation of the Zasavje coal region.
Vrtovec also stressed the importance of developing clean technologies and using domestic energy sources as Slovenia seeks to reduce its dependence on imported energy. With the addition of large-scale battery storage, the Prapretno project combines renewable electricity generation with technology designed to make the power system more flexible and resilient.
