China turned away enough clean energy to power Mexico for a year in the six months through June as its grids hit their limits, while networks in many other nations such as Australia and Japan also failed to keep pace with a surging renewables buildout.
Curtailments, or the pre-emptive rejection of wind or solar power because a grid reaches capacity, are emerging as a growing challenge to renewables globally and underscore continued reliance on fossil fuels.
China, the world's top producer of solar power, rejected 360 terawatt-hours (TWh) of clean power from January to June, up 49% from the same period a year earlier, according to a report this month by Global Energy Monitor (GEM) and the Center for Research on Energy and Clean Air (CREA).
The report's estimates for curtailments far exceed figures given by the Chinese government.
Insufficient transmission infrastructure and supply contracts that guarantee operations of newly built coal-fired power plants in China are forcing the rejection of abundant renewable output, analysts say.
"Curtailment in China is structural, not a temporary bottleneck. We expect curtailment pressure to continue through the rest of this decade," said Yuan Ren, analyst at consultancy Wood Mackenzie.
Curtailments, along with a new policy that removes a guaranteed fixed price for renewables, have contributed to a 66% drop in new solar installations this year in China. At the same time, China's coal-fired power generation is expected to rise again this year, reversing a first-in-a-decade decline.
CURTAILMENTS AFFECTING RENEWABLE INVESTMENTS
China's National Energy Administration, which stopped publishing monthly data on curtailment by province in March, said in a statement last month that 8.6% of the country's solar output and 9.1% of its wind output were curtailed in the first half of 2026.
But GEM and CREA estimate China rejected 26.1% of its total wind and solar output in the six months through June, using weather-adjusted data to account for unreported curtailment.
The National Energy Administration did not respond to a faxed request for comment.
With curtailment worsening, it's harder "to do pre-assessment of the financial viability of projects," said Shawn Shuwei Zhang, chief economist at Beijing-based consultancy Draworld Environment Institute.
Clean power investments are already shifting from standalone solar projects towards solar-plus-storage to reduce exposure to curtailment, Wood Mackenzie's Ren said.
CURTAILMENT RISING GLOBALLY
Rising curtailment extends beyond China, to the rest of the Asia Pacific and Europe.
In Australia's National Electricity Market, curtailments surged 37% to 2.93 TWh, or 7% of its wind and solar output, in the first half of 2026, while Japan's grid rejected 2.35 TWh — a jump of 34% and representing 4% of renewable output, data from their electricity markets showed.
India, the No.3 global solar generator, curtailed 8.13 TWh of solar power in the quarter ended June, its renewable energy minister said. That accounts for 14% of its solar output in the three months through June, grid data showed.
That compared with March quarter curtailment of 0.47 TWh of renewable output that includes both solar and wind, according to energy think tank Ember. Indian solar generation is, however, typically much higher in the June quarter, meaning curtailments will be higher too.
Efficient deployment and an immediate scale-up of battery storage could help stall curtailment globally, Ember analyst Kostantsa Rangelova said, adding that Bulgaria and Chile provided effective models that could be emulated.
"Chile added 4 GWh of batteries in 2025, more than doubling its installed capacity. Most of this new storage was co-located with solar plants, helping reduce curtailment," Rangelova said.
