## 4 Conclusions  
This study focuses on the consequences of the July 2024 heatwave on the Croatia's power system and replays the conditions to determine how the future expansion in renewable energy could mitigate the problem in July 2030. The findings reveal a critical vulnerability in the present state: during peak demand events, such as the July 2024 heatwave, Croatia imports up to 35% of the electricity demand, contributing to price surges exceeding 300 \(\upupup\)/MWh. The analysis foresees that by 2030, expansions in solar PV, wind, and hydro could reduce electricity imports from 27.1% to 1.6% in the summer. With favorable renewable energy availability, Croatia has the potential to become a net electricity exporter on an annual basis. The projected increase in solar PV capacity, from 200 MW to 1500 MW, and of onshore wind, from 1200 MW to 1500 MW, will increase the share of VRE generation from 15.6% in 2024 to 30.3% in 2030. Import energy dependency will be reduced; however flexible dispatchable generation will become critical, particularly CCGT, for compensating renewable energy intermittency. The simulation results indicate that the overall fossil fuel generation will increase only slightly on an annual basis, from 19.7% in 2024 to 22.0% in 2030. CCGT generation will increase by 27%, while hard coal generation will reduce by 35%, over the same period. However, fossil fuel generation is projected to increase by 62% during the summer months, particularly in July and August, to compensate for the low availability of renewable energy and to meet the elevated demand for cooling energy. Beyond 2030, further reductions of non-renewable generation will be possible with higher penetration of renewable energy, particularly onshore wind and solar PV. This approach will inevitably lead to increasing renewable energy oversupply. The present analysis assumes a wind-to-solar PV capacity ratio of 1.0. In the Croatian power system with balanced wind and solar PV capacity, 1500 MW each, the renewable energy oversupply ranges between 3.3% in the summer and 7.0% in spring and autumn, with a year-round average of 5.3%. Renewable energy oversupply increases steeply when solar PV capacity exceeds wind capacity (\(P_{\mathrm{wind}}/P_{\mathrm{solar}}\) < 1.0) and when their individual capacities exceed the baseload demand in Croatia (~1500 MW). This underscores the importance of investing in energy storage systems which would manage peak loads and renewable oversupply. Approximately 2 GWh of short-term energy storage (400 MW of discharge capacity over 5 h duration) could manage evening peak demands during summer heatwaves. Future research should aim to improve the power system model by addressing the limitations listed in Section 2. The limitations include, but are not limited to, real-world uncertainties such as power plant outages, transmission grid contingencies, fuel price fluctuations, generation redispatch, and renewable energy curtailment. The model could be expanded to neighboring countries, and possibly to the entire EU-27 to generate better predictions of the future performance of Croatia's power system. Energy storage systems, such as pumped hydro, batteries, and green hydrogen, could be integrated into the model to enable a more accurate assessment of future power systems with high shares of VRE generation. Future research could also include climate models and machine learning tools to improve the forecast accuracy of future power loads. **Author Contributions**: Conceptualization: P.B. and I.B. ; methodology, P.B. and T.S. ; software, I.W. and T.S. ; validation, I.B., I.W. and T.S. ; formal analysis, P.B. and I.W. ; investigation, P.B. and I.W. ; resources, I.B. ; data curation, I.B. and T.S. ; writing--original draft preparation, P.B. and T.S. ; writing--review and editing, I.B. and I.W. ; visualization, P.B. ; supervision, I.B. and T.S. All authors have read and agreed to the published version of the manuscript. **Funding**: This research received no external funding.