Korean Renewables Pass Coal, Grid Lags

South Korea's renewables now out-muscle its coal fleet by just 283 MW. The Korea Power Exchange put installed renewable capacity at 41,040 MW on Oct. 21, against 40,757 MW of coal, pv magazine reported.

A margin that thin could vanish with a handful of plant retirements or a single large solar commissioning. Its real fragility is elsewhere. pv magazine noted that the figures describe installed capacity, not electricity generated. In South Korea, the distance between the two is set by the grid, and the grid is losing ground.

A crossover with a short fuse

Renewables now make up 25.4% of installed capacity, the second-largest source after liquefied natural gas at 46,788 MW. The gap to LNG has narrowed to about 5,748 MW, the exchange said.

The pace explains why. Renewable capacity grew by about 3,504 MW a year between the end of 2020 and the end of 2025, about 4.3 times the roughly 807 MW added annually for LNG, pv magazine reported. The exchange said that if both trends hold, renewables could become the largest source of installed capacity within two to three years. Seoul Economic Daily reported that renewables trail the country's largest power source by 5.75 gigawatts, with some forecasts putting the takeover as early as next year. At the recent pace of growth, it calculated, renewables would catch LNG around August 2028.

Electrons with nowhere to go

Installed megawatts earn nothing if the wires cannot carry them. A National Assembly Budget Office report found that 112,430 gigawatt-hours went unproduced because of transmission constraints from 2021 through the first half of this year, Seoul Economic Daily reported. Korea Electric Power Corp. paid generators 3.1651 trillion won in make-up payments to compensate units kept offline.

The constraint is not selective. Twelve power plants nationwide currently face output restrictions because of transmission problems. At the Taean coal-fired plant, 43,590 gigawatt-hours of planned output, 24.9 percent of the total, was abandoned between 2021 and June of this year.

The mismatch in construction clocks is the root cause. Solar and other generation facilities take one to three years to build, coal plants five to seven and nuclear reactors seven to nine. Transmission lines at 345 kilovolts take an average of nine to 13 years. The Yongin project, which will spend 3.7 trillion won on 14 lines at the 345-kilovolt level, was only 1 percent complete at the end of 2025.

The queue is already visible on the ground. Solar developers in the Honam region have been waiting indefinitely since June 2024, when the local grid saturated and stopped accepting new connections. Offshore wind developers there hold connection rights for about 15.8 gigawatts through 2030, but only about 3 gigawatts are expected to be used, and roughly 10 gigawatts of rights are to be redistributed, a government official said.

Even connected solar underdelivers. Seoul Economic Daily reported that South Korean solar farms generate no more than 70% to 80% of rated capacity at peak hours, and average utilization sits in the mid-10% range. A megawatt of solar is not a megawatt of coal.

Targets that outrun the wire

Policy is pulling hard in one direction. Climate, Energy and Environment Minister Kim Sung-whan said at an Oct. 1 press conference that the ministry will "phase out coal-fired power generation by 2040," Korea JoongAng Daily reported. He said the country plans to expand renewable capacity to 100 gigawatts while keeping nuclear in the mix. The K-GX strategy, unveiled Oct. 7, commits to at least 100 gigawatts by 2030, backed by 1 quadrillion won of government-led investment over the next decade, The Korea Times reported. It also calls for high-voltage direct-current lines and higher-capacity replacement cables.

The arithmetic is steep. Meeting the 100 gigawatt target by 2030 would require roughly 15 gigawatts of additions a year starting next year, Seoul Economic Daily reported. An unnamed industry official put the floor lower but still demanding: "Considering the government's target, at least 10 gigawatts of renewable capacity will have to come online next year." Recent additions have run at about 3,504 MW a year.

The U.S. International Trade Administration notes that the 11th Basic Plan targets a 2030 generation mix with coal at 17.2% and renewables at 18.8%. Generation is the number the plan cares about, and capacity is only the precondition. The Lee Jae Myung administration, in office since June 2025, is drafting a new framework that weighs grid constraints alongside AI data-center demand.

Patches and a bigger fix

Seoul has started treating the wire as the problem. A grid plan aims to raise transmission-level hosting capacity for renewables from 119 GW to 171 GW by 2030, and distribution-level capacity from 84 GW to 110 GW, pv magazine reported. The Sept. 29 package lets new solar plants connect even where distribution capacity is full, with curtailment mandatory once output reaches rated capacity. In other words, new plants may be built and then throttled.

Storage is the other lever. The Korea Power Exchange opened a tender on Sept. 22 for 1,100 MW/6,600 MWh of six-hour storage on the mainland, plus 80 MW on Jeju Island, under 15-year contracts. Winners are due in November, and commissioning is required by February 2029. Seoul Economic Daily reported separately that the Renewable Portfolio Standard will be abolished, with annual auctions of specific volumes at long-term fixed prices starting in 2027.

A solar farm takes one to three years to build. The line it needs takes nine to 13. Korea's crossover happened on the short clock, and the wire runs on the long one.