Croatia’s growing reliance on electricity imports during the summer months is becoming a structural, long-term problem driven by climate change and weakening hydropower output, according to a report by industry body Renewable Energy Sources of Croatia (OIEH).

The group said data from the third quarter of 2025 “clearly shows that the Croatian power system is facing structural challenges arising from climate change, reduced reliability of the hydropower sector and high dependence on electricity imports in the summer months”. It warned that “the 36.6% drop in the energy value of water inflow for hydropower plants compared to last year confirms that hydropower is increasingly difficult to consider as a stable support for the system during peak load periods”.

OIEH added that climate trends were already visible, noting that “parts of Dalmatia are recording a decrease in summer precipitation of 10 to 15% per decade”, undermining the traditional role of hydropower in balancing Croatia’s grid.

Hydropower hit by dry conditions

The third quarter was marked by what the report called “extremely unfavourable hydrological conditions”. Electricity production from river inflows was “35% below the multi-year average for the third quarter”, forcing the system to lean more heavily on other sources.

Total hydropower output, including reservoirs, reached 866 gigawatt hours (GWh), down 16.3% from a year earlier. “The reduced production is a direct consequence of extremely unfavourable hydrological conditions,” OIEH said, adding that “the energy value of water inflow amounted to only 441 GWh”, or 36.6% less than in the same period of 2024.

At the same time, the amount of water stored in reservoirs fell by 423 GWh, “which further reduced the possibility of mitigating the decline in production from hydroelectric power plants”.

Despite strong growth in solar and steady output from wind, Croatia still had to import 1,210 GWh of electricity in the third quarter, equivalent to 24.9% of total available energy.

“Despite the growth in production from other renewable sources, the third quarter of this year once again confirmed the high dependence of the Croatian power system on electricity imports,” the report said. It added that “such a high level of imports is primarily due to the lack of domestic generation capacity during the peak summer load period”.

At an average CROPEX power price of €92.46 per megawatt hour, the market value of imported electricity was about €112mn. OIEH said that “this amount is approximately sufficient for an investment in approximately 100 MW of wind power plants or approximately 125 MW of solar power plants”, illustrating “the economic cost of postponing the development of domestic generation capacity”.

The group estimates that with “an additional approximately 2,100 MW of installed solar power plants during the summer months, the need for electricity imports would be reduced to a minimum”.

Solar leads renewable growth

Other renewable sources – including solar, wind, biomass and biogas – produced 1,212 GWh in the quarter, up 17.1% from a year earlier, and made up 24.9% of available energy.

Solar was the standout. “The most pronounced growth was recorded in solar power plants, which produced 389 GWh of electricity in the third quarter, which is 156 GWh more than in the same period last year, or a strong growth of 67%,” the report said. That was driven by new capacity, with “an additional 353.9 MW of solar power plants” installed between January and November 2025.

Wind output was broadly stable at 606 GWh, while biomass and biogas plants produced 217 GWh, up 9.1% year on year.

In total, renewable sources including hydropower generated 2,078 GWh, covering 42.7% of electricity consumption.

Electricity consumption in the quarter fell 7% to 4,858 GWh, mainly because of cooler weather. The average temperature was 23.5°C compared with 25.1°C a year earlier, cutting cooling demand by 273 GWh.

Even so, available electricity dropped by 7.8% to 4,864 GWh, reflecting weaker hydropower and lower fossil-fuel generation, which fell 26% due to what OIEH called “the market uncompetitiveness of fossil sources due to high production costs and the price of CO₂ emission units”.

OIEH said solar and other renewables were increasingly crucial in a changing climate. “In such conditions, other renewable energy sources, especially solar power plants, become a complementary source that can mitigate climate and market risks,” it said.

However, it warned that generation alone was not enough, as the accelerated development of RES “must be accompanied by investments in the electricity grid, system flexibility and energy storage systems to ensure a stable and reliable supply”.