The surprising problems of energy oversupply
Published: 18 Sep. 2025, 07:00
Audio report: written by reporters, read by AI
![Solar panels manufactured by Hanwha Qcells installed in Germany [HANWHA QCELLS]](https://koreaseafood.online/data/photo/2025/09/18/eee9ea65-c429-404f-ab38-9155395037a2.jpg)
Solar panels manufactured by Hanwha Qcells installed in Germany [HANWHA QCELLS]
Korea may be about to face an energy crisis this autumn — not because of an energy shortage, but a surplus.
The Ministry of Trade, Industry and Energy said on Sept. 16 that it conducted an emergency simulation drill at the Korea Power Exchange in Naju, South Jeolla, with the participation of Korea Electric Power Corporation (Kepco), Korea Hydro & Nuclear Power and others.
The drill included real-time electricity supply monitoring, output control of power generation and a review of response plans between agencies.
While solar power output typically increases in autumn due to strong sunlight, power demand may fall significantly this year during the Chuseok holiday, which stretches up to 10 days starting Oct. 3. Although blackouts are usually caused by supply shortages, they can also occur when supply far exceeds demand. The government has launched an emergency inspection of the grid in response.
Maintaining balance between electricity generation and consumption is essential to a stable power grid. Just as power output is increased in summer to meet air conditioning demand, supply must be reduced in spring and autumn when heating and cooling needs decline. The ministry expects power demand to reach its lowest point on the day of Chuseok, which falls in the middle of the long holiday on Oct. 6.
To address this potential crisis, the government plans to carry out measures such as temporary reductions in power generation, known as output control. It will minimize operations at coal-fired plants and may also utilize the demand response (DR) system, under which predesignated electricity users adjust usage upon request.
The sharp rise in solar and wind capacity during the Moon Jae-in administration has led to recurring oversupply issues in spring and autumn. Output control has been increasing as a result.
Hanwha Qcells' solar power panels in Borrego Springs, California.
Output control volume in the first half this year — excluding Jeju Island — reached 164.4 Gigawatt Hour (GWh), which is 12.5 times the total for all of last year, or 13.2 GWh, according to the ministry. That amount of energy could power up to 14 million households for a day, assuming an average daily usage of 300 to 400 kWh per household.
Last year, output control for solar power occurred 26 times with 7,899 MWh, and wind power 16 times with 157 MWh. In just the first half this year, solar power was curtailed 44 times with 64,057 MWh and wind 37 times with 8,249 MWh, far surpassing 2023 figures.
The output control rate — the proportion of curtailed power to total estimated generation — has also surged during the same period, from 0.03 to 0.3 percent for solar and from 0.005 to 0.4 percent for wind. This year, curtailment orders have even extended to baseload power sources such as nuclear and fuel cell generators.
A critical issue is the failure to expand transmission infrastructure in step with the growing electricity supply. Data from the Korea Power Statistics Information System show that while solar capacity grew from 2.5 GW in 2015 to 27.4 GW at the start of this year, transmission lines expanded by only 8.5 percent over the same period.
![A view of a solar power plant installed on farmland in Seogwipo, Jeju [JEJU]](https://koreaseafood.online/data/photo/2025/09/18/5b3f58d0-f1db-4bd9-958a-864c9c90cc63.jpg)
A view of a solar power plant installed on farmland in Seogwipo, Jeju [JEJU]
In other words, generation capacity grew more than tenfold, while the "roads" for distributing electricity have barely changed. Resistance from local communities and environmental regulations have blocked further development.
In the past, output control was limited to Jeju Island, but starting in 2024, it has been occurring on the mainland as well. Experts say the country’s grid stability is now seriously compromised.
“Output control is an unavoidable consequence of expanding renewable energy,” said an industry official. “But since Korea is essentially an ‘electricity island’ with no international grid connections, more frequent curtailments will inevitably increase the risk of blackouts.”
A major blackout in Spain last April was also attributed to excessive reliance on renewable energy. Spain, a European leader in renewable power, typically derives about 60 percent of its electricity from renewables. On the day of the outage, solar accounted for nearly 80 percent of production, destabilizing the grid. Even with its connection to the broader European grid, Spain could not prevent the blackout through imports and exports.
![A picture of Hanwha Qcells' solar panels in California, installed in May 2024 [HANWHA QCELLS]](https://koreaseafood.online/data/photo/2025/09/18/ea913af5-4e90-4cb6-aba9-335898bfb083.jpg)
A picture of Hanwha Qcells' solar panels in California, installed in May 2024 [HANWHA QCELLS]
Despite these risks, President Lee Jae Myung urged an accelerated rollout of renewables at his 100-day press conference on Sept. 11. “The fastest way to supply electricity is through solar and wind,” he said, instructing officials to “launch full-scale construction within one to two years.”
The government has raised next year’s renewable energy budget by 50 percent compared to this year. As a result, output control of renewable energy is expected to continue increasing for the time being.
“In the long term, we need to expand the transmission grid and strengthen energy storage systems (ESS), but in the short term, output control is unavoidable,” said a Ministry of Industry official.
“Solar output control is carried out manually, with power producers flipping switches when notified by text message,” said Yoo Seung-hoon, professor of future energy convergence at Seoul National University of Science and Technology.
“Some fail to comply or demand compensation, which adds pressure to raise electricity rates. The need for a balanced policy that combines compensation and participation before grid instability from output control leads to major blackouts is now more crucial than ever."
This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY KIM WON [[email protected]]
with the Korea JoongAng Daily
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