State-owned Hidroelektrarne na Spodnji Savi (HESS) inaugurated two photovoltaic units of 9.34 MW in total peak capacity next to its Brežice hydropower plant. Together with the one installed earlier, they formed the largest solar complex and hybrid power plant in Slovenia. The combination enables production optimization through saving water in the Brežice reservoir for times of peak demand.

With its 6 MW in peak capacity, FEBR-D3 was the biggest solar power plant in Slovenia when it was commissioned in 2023. It is located on the sediment landfill at the Brežice hydroelectric plant’s reservoir and integrated with the facility into a hybrid power plant.

The operator, state-owned Hidroelektrarne na Spodnji Savi, launched the trial operation of another two PV units in August. Now it is the largest complex of solar power plants in Slovenia, Chief Executive Officer Boštjan Pišotek said this week at the inauguration of FEBR-D1 and FEBR-D2, of 9.34 MW in combined peak capacity.

The new units span a total of 9.4 hectares at the sediment deposits. They consist of 14,952 bifacial modules.

Croatian company Končar was the contractor for the investment of EUR 4 million. Construction lasted 14 months. The estimated annual output of the new segments is 10.5 GWh, translating to 17.4 GWh for the entire 15.3 MW.

Rifelj: Energy transition implies responsibility toward space, people, nature

Brežice is a run-of-river hydropower plant with pondage, so solar power enables it to optimize production by saving water for times of peak demand. The reservoir’s useful capacity is 3.4 million cubic meters.

For its solar farms, HESS used areas that were already part of energy infrastructure

Minister of the Environment and Spatial Planning Polona Rifelj said at the event that the energy transition does not only mean building new production capacities, but also responsible project siting and care for the impact on people, nature and local communities.

On that note, HESS used areas that were already part of energy infrastructure. To preserve the habitat of the sand martin and European bee-eater, it has built a replacement nesting wall for the birds.

One segment of Brežice solar complex not connected to hydropower plant

The Brežice photovoltaics aren’t a single power plant. The grid availability and proximity situation required D1, of 4.8 MW, to be connected to a 20 kV of Elektro Celje, the distribution system operator in the area.

D2, with its 4.6 MW, is linked through the hydroelectric plant to a 110 kV network of Slovenia’s transmission system operator ELES, as is D3.

The three equal Kaplan turbines in Brežice amount to 47.4 MW overall. They generate an average 161 GWh in total per year.

HESS is owned by GEN Group (51%) and Holding Slovenske elektrarne (HSE), 49%.