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In a new weekly update for pv magazine , Solcast, a DNV company, reports that the US Midwest enjoyed exceptional conditions with irradiance up to 10% above normal for the entire year, while areas along the Gulf Coast and much of the West Coast experienced slightly below-average sunshine.
2024 featured regional contrasts in solar irradiance across the United States. The Midwest enjoyed exceptional conditions with irradiance up to 10% above normal for the entire year, while areas along the Gulf Coast and much of the West Coast experienced slightly below-average insolation. According to analysis using the Solcast API , ERCOT (the Texas power grid) and PJM (the Eastern Interconnection grid) both posted better capacity-adjusted performance over the year compared to long-term trends, while CAISO (the California power grid) performed slightly below average. However, since solar capacity is increasing year-over-year, this analysis is based solely on weather effects on current capacity.
Midwest solar performance stood out in 2024, with states including Indiana, Illinois, Missouri, Iowa, and Kansas experiencing solar irradiance 10% above average. Adjacent areas from Michigan to Idaho, the Great Plains, and West Texas also saw irradiance levels up to 5% above normal. Despite some variation throughout the year, consistently clear conditions, notably an anomaly of over 20% in October, contributed to the strong annual performance of solar assets in the Midwest.
These regions coincided with areas severely affected by drought, which likely contributed to reduced cloud cover and increased sunshine levels. This surge in solar output translated into increased output for regional grids, with ERCOT achieving a 2.7% increase in capacity-normalized solar output and PJM recording a 4% increase compared to average values.
In contrast, the West Coast had a weak year for solar generation, with northern areas recording irradiance up to 5% below average, while most of California saw only slight deviations from the norm. The primary cause was the presence of several low pressure systems from the Pacific, which brought cloudiness and moisture to the region. These conditions contributed to CAISO seeing a modest 0.8% decrease in capacity-normalized solar output in 2024 relative to average.
States along the Gulf Coast, including East Texas and Louisiana, also faced declining solar irradiance, with levels as much as 5% below average. Southeast Texas experienced a year of normal to above-normal precipitation after several years of drought. This shift was due to above-average sea surface temperatures, which channeled more moisture inland and increased cloud cover. These conditions reduced solar energy potential in the region, although drier, clearer conditions inland in Texas caused ERCOT to continue to outperform the long-term trend.
Despite these regional variations, the United States as a whole saw slightly higher irradiance in 2024, with levels 0.8% above climatic averages. Major Midwestern cities, including Kansas City and St. Louis, saw above-average irradiance, and Chicago broke its record for average irradiance this year. This reinforces the region’s strong performance in 2024.
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 300 companies managing over 150 GW of solar assets worldwide. |
