• Data only include firms above a 'designated size' -NBS
• Electricity output growing faster than monthly NBS data shows -Ember
• Better data key for tracking progress on carbon reduction -analyst

SINGAPORE/BEIJING, Sept 20 (Reuters) - Surging small-scale renewables generation is helping China address growing power demand and slashing the role of coal in the country's power mix, but Beijing's widely followed monthly data reports omit output from the fast-growing sector.

Data from the National Bureau of Statistics (NBS), which publishes monthly bulletins on key economic indicators, only surveys industrial firms with at least 20 million yuan ($2.84 million) of annual revenue from their main operations.

For the renewables sector, that has resulted in the NBS leaving out a significant chunk of generation from small-scale sources powering residences, offices and industries, making it more difficult to gain insights into China's economy.

The data is also masking some of the progress by the world's top greenhouse gas emitter in reducing the share of coal in electricity generation.

"Well-structured monthly reporting on energy and electricity data will be key for China to track progress against its carbon goals," said Lauri Myllyvirta, senior fellow at the Asia Society Policy Institute.

The NBS data shows China's power generation grew 6.4% in the first half of 2024. However, data from London-based energy think tank Ember, which calculates output from small-scale renewable energy using data from China's National Energy Administration, shows electricity output grew 7.3%.

The NBS provides monthly updates and has archives with uniform reporting patterns starting in the late 1980s. But NEA, China's energy regulator, does not provide a public schedule before disclosing data. It also stopped reporting information on utilisation rates in June, making periodically tracking generation from renewables difficult.

NEA did not respond to requests seeking comment and the NBS declined to comment beyond noting it surveys firms of a "designated size".

When analysts and investors "are looking at the total generation number and it is grossly underreported, especially the growth, then they are getting a skewed picture of what is happening in the economy," Myllyvirta said.

The discrepancy is mainly due to growth in additions of distributed solar over the last three years in China, with smaller installations growing at nearly twice the rate of large utility-scale solar farms - the main driver of renewable capacity additions in China in the previous decade.

Distributed solar, which includes rooftop panels, describes small installations supplying power near where it will be used.

Ember data shows the share of wind and solar in China's power output to be 20.3% during the first half of 2024, much higher than the NBS figure of 15%.

NBS places the share of fossil fuels in the country's power generation at 67.8%, compared with Ember's estimate of 62.3% based on NEA data.

"China NBS's generation data for wind and especially solar only capture some of the generation, whereas their capacity figures show the full picture," said Xuyang Dong, China energy policy analyst at Sydney-based think tank Climate Energy Finance.

($1 = 7.0454 Chinese yuan renminbi)

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https://www.reuters.com/sustainability/climate-energy/china-monthly-economic-reports-understate-power-output-small-scale-renewables-2024-09-20/