In recent days, Greece’s electricity market has seen wild swings in wholesale prices within the same 24-hour period. During the day, abundant sunshine and strong summer winds — the seasonal “meltemia” — send renewable generation from solar and wind farms soaring to record levels, often exceeding the country’s demand. This oversupply can push wholesale prices into negative territory by midday. But when night falls and solar output drops to zero, the grid must switch to more expensive natural gas plants, and prices can skyrocket in a matter of hours.
The pattern has been intensified by a heatwave gripping southern and southeastern Europe, which fuels heavy evening demand for air conditioning. While similar fluctuations have been observed in neighboring Bulgaria, Romania, and Hungary, Greece’s imbalance between supply and demand is far more pronounced. Grid congestion has forced operators to curtail renewable output at levels once seen only in the low-demand months of spring and autumn. In August alone, dozens of gigawatt-hours of green energy have been discarded — a blow to producers who are also facing high balancing costs. Some are now deliberately withdrawing power from the system, using virtual power plant platforms to avoid losses when prices turn negative.
At the root of the volatility is a structural problem: Greece has rapidly expanded its renewable capacity but has lagged in developing large-scale energy storage. With no way to store excess daytime electricity for nighttime use, the grid is trapped in a cycle of daytime oversupply and evening shortages. The country’s hot, dry summers further complicate the picture, as low hydroelectric output leaves few alternatives to expensive thermal generation once the sun goes down.
Energy experts say the solution lies in major investment in storage technologies, particularly batteries, as well as in expanding the transmission network and strengthening cross-border interconnections. This would allow surplus renewable power to be exported during the day and help smooth out evening price spikes. Until then, Greece’s paradox will remain: one of Europe’s sunniest and windiest nations, awash in green electricity by day, but still paying a premium for power by night.
