Greece’s power system is experiencing increased strain as a prolonged heatwave drives electricity demand higher, with air conditioning loads pushing 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. Nearly all available dispatchable generation units have been kept 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 declines. The operating pattern reflects the need to balance daytime solar generation with conventional capacity during peak and ramping periods.
After sunset, photovoltaic production falls and wind generation becomes a key factor for balancing supply and demand. Strong wind output reduces the need for gas and lignite plants, while weaker conditions increase their role in covering the evening demand gap. Weather variability therefore affects short-term system stability through changes in renewable output.
Reserve capacity and generation availability
The heatwave affecting 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 stay online throughout the summer, with only one unit currently offline due to technical maintenance. ADMIE has 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 beyond the current summer period.
Hydropower support from higher reservoir levels
PPC hydropower is providing additional flexibility for balancing needs during peak demand periods. Reservoir levels at PPC facilities are estimated to be 20–25% higher than last year. Higher storage supports the system’s ability to respond to short-term fluctuations in both demand and renewable generation.
