(Nova Gorica, 21 January 2026) Soške elektrarne Nova Gorica (SENG), which is part of the HSE Group, concluded a contract with the Japanese partner, Hitachi Mitsubishi Hydro Corporation (HM Hydro), to carry out the second overhaul of the generator in the Avče pumped-storage hydro power plant, the first and so far the only pumped-storage hydro power plant in Slovenia. HM Hydro will execute the overhaul as the only authorised repair company of the key technological equipment manufacturer.
The Avče pumped-storage hydro power plant is one of the major energy facilities in Slovenia. With its advanced energy storage technology, it plays a crucial role in ensuring the stability of the power system, the offsetting of energy generation and consumption, and the integration of renewable energy sources. The power plant has been in operation since 2010 and is one of the first reversible pumped-storage hydro power plants with variable rotation speed in pumping mode in Europe.
Multi-annual preparations and meticulously planned project
Thoroughly planned preparations for the second overhaul took the SENG company several years. These preparations included the drafting of investment documentation, technical analyses of the condition of the equipment, definition of the scope of works, and challenging negotiations with the overhaul contractor. The second overhaul is planned for 2027, which is eight years after the successfully implemented first overhaul in 2018 and 2019. Its purpose is to carry out maintenance measures and replace worn-out parts to ensure the reliable, safe and long-term operational capacity and availability of the Avče pumped-storage hydro power plant until its next overhaul, anticipated around 2036.
Key investment in production reliability
The SENG company will finance the overhaul with its own resources. It will take about seven months and, in addition to the overhaul of the generator, will also include numerous other investment maintenance works.
At the signing of the contract, Mitja Gorjan, Chief Executive Officer of the SENG company, highlighted, “The Avče pumped-storage hydro power plant is a strategic energy facility that has a prominent role in providing power within the balance responsible party of Holding Slovenske elektrarne (HSE) as well as more broadly in the Slovenian power system. The company is aware of its responsibility when managing this hydro power plant. The conclusion of the contract for the second overhaul is the result of several years of expert and carefully controlled preparations. The conclusion of negotiations at the end of 2025 resulted in a significant step forward on the path to ensuring these objectives.”
Gorazd Leban, Maintenance Manager in the SENG company and Project Manager of the overhaul, added, “The overhaul of such a sophisticated and technologically advanced generator is an exceptionally complex project. The experience from the first overhaul revealed the importance of detailed preparations, good harmonisation and cooperation with the only authorised repair company of the equipment manufacturer. The selected contractor ensures the highest level of expertise and safety during the implementation of works.”
Dr Tomaž Štokelj, Chief Executive Officer of HSE, underlined that the Avče pumped-storage hydro power plant is a major component in Slovenia’s green transition, “The pumped-storage hydro power plant enables the storage of electricity during times of production surpluses and its release into the grid during times of increased consumption. By doing so, it significantly contributes to the technical and economic balance of the power system, reduction of price fluctuations on the electricity market, better integration of renewable energy sources, and the decarbonisation of the Slovenian energy sector. This is a strategic energy facility of national importance and a key element of the Slovenian energy infrastructure that enables the reliable operation of the system and represents a major component in the transition to a low-carbon society, the spearhead of which in Slovenia, is the HSE Group.”
