Croatia transmission demand peak recorded on 11 August
Croatia set a new transmission-system electricity demand record on 11 August, with average load reaching 3,400 MW between 20:00 and 21:00. The figure reflects a summer evening ramp in a system affected by distributed solar generation.
Transmission system operator HOPS recorded 64 GWh of electricity withdrawn from the transmission network over the full day. The reported transmission demand does not include electricity generated and consumed directly behind the meter. This omission is particularly relevant for household and commercial solar installations.
Behind-the-meter solar shifts daytime and 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. It also creates a growing gap 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 periods. That generation then falls rapidly towards evening while air-conditioning and residential demand can remain elevated. As a result, the highest stress on the transmission system can occur after solar production declines rather than during the hottest afternoon hours.
Comparison with Slovenia’s winter peak and cross-border trading effects
The Croatian record contrasts with neighbouring Slovenia, where the highest hourly transmission load of 2,300 MW was recorded between 08:00 and 09:00 on 8 January 2026. That peak occurred during an exceptionally cold period.
The two markets therefore experience different seasonal demand extremes, with Slovenia’s record linked to winter heating and cold-weather conditions. Croatia’s peak was registered during the summer holiday and cooling-demand season. The intraday pattern can affect trading conditions for cross-border flows with Slovenia, Hungary, Bosnia and Herzegovina, and Serbia.
Implications for assessing rooftop solar beyond annual output
The 3.4 GW record also highlights that installed behind-the-meter solar cannot be assessed solely by its contribution to annual energy production. As rooftop penetration rises, its impact on network demand, peak timing, and flexibility requirements becomes more significant. This is reflected in how evening conditions can tighten as solar output declines.
