Greece’s power system is facing higher operating stress as a prolonged heatwave pushes electricity demand up, with air conditioning loads driving the grid toward seasonal peaks. Since the start of the heatwave, peak demand has moved from typical summer levels of 6,000–6,500 MW to around 9,000 MW. The increase has required nearly all available dispatchable generation units to stay in operation to maintain system stability.
Natural gas-fired plants have been running continuously since 24 June. PPC’s lignite unit Ptolemaida V has also been activated, particularly during evening hours when solar output falls and flexible thermal generation is needed to cover demand. The operating pattern reflects the need to balance daytime solar dominance with conventional capacity during peak and ramping periods.
Renewables output shifts after sunset
After sunset, photovoltaic production declines and wind generation becomes a key factor for balancing the system. Strong wind output reduces the need for gas and lignite plants, while weaker conditions increase their role in covering the evening demand gap. Weather-driven changes in renewable output therefore affect short-term system stability.
Reserve capacity and summer thermal availability
The heatwave across much of Europe has also highlighted the importance of reserve capacity. Greece’s transmission system operator ADMIE said available generation is adequate even if peak demand approaches 10,000 MW. ADMIE’s assessment indicates the system remains secure under current stress levels.
Nearly the entire gas-fired fleet is expected to remain online throughout the summer, with only one unit currently offline due to technical maintenance. ADMIE has also reportedly requested that PPC keep Ptolemaida V available at least through the end of the 2026/27 winter season. The request points to continued reliance on dispatchable thermal capacity during colder months.
Hydropower provides additional flexibility
Hydropower is contributing additional flexibility to balance demand and renewable generation changes. Reservoir levels at PPC facilities are estimated to be 20–25% higher than last year. This level is expected to provide a stronger buffer during peak demand periods and help manage short-term fluctuations in both load and renewable output.
