Renewables
Asian solar irradiance swings sharply in September
September saw unusual solar irradiance variations across Asia driven by active weather systems and tropical storms.
Key points
- Japan and Borneo experienced below-average solar irradiance due to storms and wildfire smoke.
- Northern China, Korea, the Philippines and eastern Indonesia recorded substantially higher sunshine levels.
- An active typhoon season and strengthening El Nino influenced regional weather patterns.
Weather extremes impact solar output
Solar irradiance levels across Asia experienced significant deviations in September, with several locations recording departures of roughly 30 percent above or below normal ranges, according to Solcast API data reported by pv magazine.
Japan and Borneo faced particularly cloudy conditions, recording roughly 70 percent of typical September irradiance levels. Japan experienced impacts from tropical storms and multiple typhoons, while Borneo dealt with wildfire smoke alongside heavy cloud cover later in the period.
Regional contrasts across Asia
Conversely, brighter conditions prevailed in northern China, Korea, the Philippines and parts of eastern Indonesia. pv magazine noted that southern China's Yunnan-Guizhou Plateau registered the highest positive anomaly on the continent, climbing up to 30 percent past historical averages.
An active regional typhoon season contributed heavily to these variations, with extreme sea surface temperatures aiding storms such as Dujuan, Surigae and Choi-wan. These systems generated extensive cloud cover and rainfall that suppressed solar generation in affected areas.
Outlook for late 2026
Looking toward the final quarter of the year, weather forecasts anticipate sunnier conditions across most of Southeast Asia. Meanwhile, strengthening El Nino conditions are expected to bring increased cloud cover to eastern China and Japan.
Original reporting
This article draws on the following reports. Read them in full on the publishers’ sites.
Context from CEII
Renewables are the fastest-growing part of the world’s energy system. The COP28 goal is to triple capacity by 2030, and solar mini-grids are the fastest route to power for millions of people without electricity.
28.4% of electricity in China was renewable in 2021Written by the CEII Desk, the Centre’s automated newsroom, from the reporting credited above and CEII’s own data. Facts are attributed to their sources; the publishers have not reviewed this article. Spotted an error? Tell our editors.
