Record cold, dust storms shape complex winter for South American solar

Winter in South America brought sharp month-to-month contrasts for solar generation, as the region experienced swings between unusually cold conditions and clear skies. While June and July largely offset one another in terms of irradiance anomalies, August closed the season with more balanced conditions, resulting in a slight net increase in available irradiance across large parts of the continent. Meanwhile, extreme cold in the southern cone tested energy systems and brought rare winter events to some of the sunniest regions in the world.

June and July delivered near-opposite irradiance patterns, effectively neutralising seasonal anomalies until August. Across the Andes, Brazil, Uruguay, Paraguay, and into parts of northern South America, the final winter picture showed a modest uptick in available solar resource. The month-to-month variability was driven by reversals in dominant weather patterns, with cloudier-than-usual conditions in one month giving way to clearer skies in the next. August provided more consistent conditions, leading to much of the continent experiencing a close-to-average winter, despite variation from month to month, as seen in the below sample PV site modelling.

Despite a neutral ENSO state in the Pacific, a rare Atlantic Niña event added complexity to regional weather dynamics. Unlike its Pacific counterpart, the effects of the Atlantic Niña are less well known but is still associated with shifts in rainfall distribution in Brazil and the Amazon basin. While direct impacts on solar irradiance remain difficult to quantify, shifts in cloud cover and precipitation patterns linked to the Atlantic ocean may have played a role in the variability seen across Brazil.

A notable weather event impacted renewable generation and energy demand at the end of June, when a polar anticyclone settled over southern South America. This high-pressure system locked in frigid air, pushing Argentina and Chile to record some of their coldest temperatures in decades – the lowest globally outside of polar regions. Energy demand spiked sharply, leading to blackouts and natural gas shortages in several regions. The cold snap was sufficiently strong enough to produce snow in Chile's Atacama Desert, an area typically noted for its dryness and high solar resource.

In Peru, a major dust storm in July offered a clear example of how aerosols can match or even exceed cloud in their impact on solar irradiance. Imagery from NASA's Aqua satellite showed thick plumes of dust being driven inland by strong winds, where they collected along the western slopes of the Andes. The resulting irradiance losses were more significant than those caused by dense cloud cover, highlighting the relevance of aerosol monitoring in arid and semi-arid regions such as the west coast of South America.

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