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In a new weekly update for pv magazine , Solcast, a DNV company, forecasts drier and sunnier conditions next winter in key solar zones in the southern United States, Mexico and Brazil, driven by La Niña conditions.
Seasonal forecasts for the coming winter point to drier and sunnier conditions for the key solar regions of Texas, California, the southeastern United States, Mexico and Brazil. The forecasts also call for reduced precipitation and cloud cover across large areas of North and South America, excluding Central America and remote parts of Canada.
The forecast is based on La Niña conditions in the tropical Pacific Ocean, whereby tropical convection favors the western end of the ocean. Reduced convection over tropical waters of the eastern Pacific leads to reduced cloud and storm activity downstream over adjacent subtropical and mid-latitude continental areas of North and South America, where solar resources are located.
The current consensus among modelling agencies leans towards “neutral” conditions – that is, neither El Niño nor La Niña, but rather on the La Niña side of the spectrum. Most models suggest that while conditions should remain largely within the neutral range, there is a small chance that La Niña could strengthen. The US agency NOAA stands out as one of the few that still forecasts La Niña conditions will develop through the winter. This is a change from previous forecasts, which anticipated a further move away from neutral conditions.
Although the models differ on the strength of La Niña boundary conditions in the Pacific Ocean, they show fairly good agreement on the resulting impact of clouds and precipitation on nearby land areas. This is especially true for the United States and Mexico, where reduced precipitation is projected, meaning reduced cloud cover and favorable conditions for solar generation.
However, in Central America, the outlook is less favourable, with above-average rainfall expected in many areas that could impact solar production. In South America, the picture is less uniform. While drier than usual conditions are expected in Brazil, Uruguay and Argentina, key regions for solar generation, in other parts of South America there is less consensus among weather models, indicating that solar producers and grid operators should expect more varied conditions across the continent.
Despite consensus among models on the likely impact of clouds and precipitation over North America, when we look back at similar neutral to weak La Niña years in recent history, we see a less consistent pattern, including parts of Texas that have the opposite anomaly, experiencing more clouds and precipitation. This analysis shows the uncertainty inherent in seasonal forecasts and also highlights that La Niña is not the only phenomenon that affects seasonal weather conditions. For example, changes in Arctic storm tracks can also influence winter conditions over the U.S., but these changes are not predictable more than three to four weeks in advance at most.
Solcast produces these figures by tracking clouds and aerosols at 1-2 km resolution on a global scale, using satellite data and proprietary AI/ML algorithms . This data is used to drive irradiance models, allowing Solcast to calculate irradiance at high resolution, with a typical bias of less than 2%, and also cloud tracking forecasts. This data is used by over 350 companies managing over 300 GW of solar assets worldwide. |
