Government Launches 107-Day Solar Power Oversupply Response
Spring has effectively begun, with increased solar power generation due to sunny weather and decreased electricity consumption for heating and cooling. The government has decided to operate a “power supply and demand countermeasure period” for a record 107 days to address the risk of a large-scale blackout caused by oversupply from solar power. Solar power is highly volatile, with instantaneous generation prediction error rates reaching up to 40%, making it the top concern for power authorities. Experts warned, “If we fail to manage this volatility, a major blackout like Spain’s could easily occur in South Korea.”
◇Increasing Spring Emergency Response Periods Each Year
The Ministry of Climate, Energy and Environment announced on the 26th that it will operate the “2026 Power Supply and Demand Stabilization Countermeasure Period” from the 28th of this month to June 14th, totaling 107 days. Spring is a season when power demand is low due to reduced heating and cooling needs, while solar power generation peaks, exacerbating oversupply.
The government began operating spring power supply and demand countermeasure periods in spring 2023, when instability from excess solar power generation first became a serious issue. The initial period ran from April 1st to May 31st (61 days), expanding to 72 days in 2024, 93 days in 2025, and now 107 days this year. Over just three years, from 2023 to 2026, the spring solar power response period has nearly doubled.
This year’s official countermeasure period starts on February 28th, but the Korea Power Exchange has already entered emergency operations since the Lunar New Year holiday. During the holiday, power demand plummeted due to reduced travel and factory operations, and mild weather further decreased heating needs. According to the exchange, minimum power demand on the 17th, Lunar New Year’s Day, fell to 33,548 MW (megawatts), lower than the Ministry’s initial forecast of 37,600 MW. Korea Power Exchange employees, including Acting Chairman Kim Hong-geun, reportedly managed the situation through 24-hour shift work throughout the holiday.
Electricity becomes problematic not only when supply is too low but also when it is too high. Imbalances in supply and demand can destabilize grid frequency, leading to blackouts. In the past, the main risk was supply shortages during peak summer and winter demand. However, with the growing share of renewables, oversupply during low-demand periods like spring, autumn, and holidays has become a greater concern.
◇Maximum 40% Solar Power Prediction Error
The Ministry plans to minimize coal power plant operations during this countermeasure period and reduce output from some generators if necessary. In unavoidable cases, it may even control output from nuclear power plants, which are rigid power sources. While prior notice is the norm, real-time adjustments may be required in case of sudden weather changes.
The Korea Power Exchange is most concerned about rapid weather changes. South Korea’s power market operates on a “day-ahead market” system, where generation plans for the next 24 hours are finalized the day before. While nuclear, coal, and gas plants can meet planned output, solar power depends heavily on weather forecast accuracy. According to the exchange, hourly solar power prediction error rates can reach up to 40%.
For example, if solar power generation is predicted to be 10 GW (gigawatts) at 1 p.m. the next day but actual output is 6 GW or 14 GW, nuclear, gas, or coal plants must rapidly adjust to compensate. Delays or insufficient adjustment capacity could severely destabilize grid frequency.
Former Korea Power Exchange Chairman Cho Young-tak stated, “If we fail to respond in real-time to renewable energy volatility, a major accident like Spain’s blackout could easily happen in South Korea,” adding, “We must continuously explore ways to mitigate solar power oversupply.”