Slovenia is advancing plans for the Družmirje Floating Solar Power Plant (Družmirje FSPP), a 140 MW project set to become the country’s first and Europe’s largest floating solar array to date. The plant, located on Lake Družmirje near Šoštanj, is expected to generate 140 GWh of electricity annually, enough to supply approximately 35,000 Slovenian households. This initiative is a crucial step in Slovenia’s green transition, particularly for the Savinja-Šalek coal region, aiming to diversify electricity production and reduce greenhouse gas emissions.
A Pivotal Project for Slovenia’s Energy Transition
The Družmirje FSPP represents a significant milestone in Slovenia’s efforts to shift away from coal dependency and embrace renewable energy sources. The project is being developed by Holding Slovenske Elektrarne (HSE), Slovenia’s state-owned power generation company. Lake Družmirje, an artificial lake formed by decades of lignite mining, provides an ideal location for the innovative floating solar installation.
Project Scope and Capacity
With an indicative power of up to 140 megawatt-peaks (MWp) and an estimated annual production of 140 gigawatt-hours (GWh), the plant is designed to cover up to half of Lake Družmirje’s surface. This substantial capacity will position it as Slovenia’s largest solar project and, upon completion, potentially Europe’s largest floating solar array, surpassing a 74.3 MW array in France inaugurated in June 2025.
Timeline and Funding
Spatial planning activities for the Družmirje FSPP are currently underway, with a public consultation having taken place in late 2025. The decree of the spatial plan is anticipated in the fourth quarter of 2025. Construction is tentatively scheduled to begin by the third quarter of 2026, with electricity production expected to commence within the first quarter of 2027. The estimated capital expenditure for the project is around €100 million, which will be funded through HSE’s own resources, loans, and support from the European Union’s Just Transition Fund.
Strategic Importance for the Šalek Valley
The floating solar plant is a critical component of the Šalek Valley’s restructuring and green transition. This region has historically been dependent on coal mining and the Šoštanj thermal power plant. The Družmirje FSPP aims to compensate for the upcoming closure of the coal-fired plant, ensuring an affordable thermal energy supply for the area and supporting the local economy’s shift towards cleaner energy.
The project also includes plans to develop the surrounding area for tourism, sports, and recreation, enhancing the social and financial benefits for the local population. HSE has committed to preserving the lake’s ecosystem, including birds and aquatic life, and will adapt the shore for various activities. The installation will be positioned between 150 and 400 meters from the shore to maintain the lake’s ecological integrity.
Advantages of Floating Solar Technology
Floating solar photovoltaic (FPV) systems offer several distinct advantages, making them an attractive option for renewable energy expansion, particularly in regions with limited land availability.
Efficient Land Use
One of the primary benefits of floating solar farms is that they do not require valuable land, which can be a limited resource, especially in densely populated or agricultural areas. By utilizing existing water bodies like reservoirs, quarry lakes, or even artificial lakes like Družmirje, FPV plants free up land for other purposes.
Enhanced Efficiency
Water bodies naturally cool solar panels, which can significantly increase their efficiency and energy output compared to land-based systems that may suffer performance drops in high temperatures. This cooling effect can lead to an increase in energy production by as much as 5% to 15%. The water surface can also reflect sunlight, potentially increasing the amount of solar energy captured by bifacial panels.
Environmental Benefits
Floating solar panels can contribute to water conservation by reducing water evaporation from the covered surfaces, which is particularly beneficial in drought-prone regions. The shade provided by the panels also helps to minimize the penetration of light into the water, thereby controlling algae growth and improving water quality. Additionally, these systems can help prevent shore erosion from strong winds.
Slovenia’s Broader Renewable Energy Ambitions
The Družmirje FSPP aligns with Slovenia’s ambitious national and EU-mandated renewable energy targets. Under its updated Integrated National Energy and Climate Plan (NEPN), Slovenia aims to achieve a target of at least a 30-35% share of renewable energy consumption by 2030, with a 52% share in the electricity sector.
Slovenia has been actively increasing its solar capacity, reaching around 1.5 GW by the end of the first half of 2025, with significant deployment in 2023 and 2024. In 2023, the country surpassed its EU-mandated target of a 25% renewable energy share in gross final energy consumption, largely driven by solar energy expansion, achieving 25.07% without statistical transfers for the first time. The electricity sector saw a notable increase in renewable energy share, rising by 4.88 percentage points to 41.89%.
With strategic investments and projects like the Družmirje FSPP, Slovenia is firmly positioning itself as a leader in the green energy transition, contributing to a sustainable and competitive energy supply for the future.
