11 August transmission-system demand and rooftop solar impact
Croatia recorded a new transmission-system electricity demand record on 11 August, with average load reaching 3,400 MW between 20:00 and 21:00. The record is linked to a summer evening ramp in a system influenced by distributed solar generation. Transmission-system operator HOPS reported the timing of the highest average load during the evening period.
HOPS recorded 64 GWh of electricity withdrawn from the transmission network over the full day. Actual nationwide consumption was higher because the transmission figures exclude electricity generated and consumed directly behind the meter. This includes output from household and commercial solar installations.
Daylight suppression and a sharper evening load shape
Croatia has around 600 MW of residential rooftop solar, according to the report. The capacity increasingly suppresses visible network demand during daylight hours. This creates a growing difference between underlying electricity consumption and demand measured at transmission level.
The daily load shape becomes more pronounced as solar output reduces centrally supplied electricity during sunny hours. Solar generation then falls rapidly towards evening while air-conditioning and residential demand can remain elevated. As a result, centrally supplied demand can shift later in the day rather than peaking during afternoon hours.
Regional comparison with Slovenia’s winter peak
The Croatian system record between 20:00 and 21:00 highlights that highest stress on the transmission system can occur after solar production has declined. In neighbouring Slovenia, the highest hourly transmission load was 2,300 MW. That level was recorded between 08:00 and 09:00 on 8 January 2026 during an exceptionally cold period.
The two markets therefore show different seasonal demand extremes. Slovenia’s record reflects winter heating and cold-weather conditions, while Croatia’s was set during the summer holiday and cooling-demand season. These differences affect how intraday conditions develop across the year.
Cross-border trading relevance and limits of annual energy metrics
Croatia’s summer profile combines tourism-driven consumption with a growing distributed solar base. The report says this can produce relatively comfortable daytime balances followed by materially tighter evening conditions. Intraday changes become increasingly relevant for cross-border flows with Slovenia, Hungary, Bosnia and Herzegovina and Serbia.
The 3.4 GW figure also shows that installed behind-the-meter solar cannot be assessed solely by its contribution to annual energy production. As rooftop penetration rises, its influence extends to network demand levels, peak timing and flexibility requirements. Those impacts are described as becoming as important as total electricity produced.
