| Work Detail |
In its latest 2023 update for pv magazine , Solcast, a DNV company, presents a long-term analysis of the historical average irradiance on Christmas Day.
There are no holidays for solar production. As many cultures around the world prepare for a holiday season, the Solcast team has conducted a long-term analysis of the historical average irradiance on Christmas Day, and a look at the forecasts for Europe and the United States, using Solcast API data.
Christmas Day is just a few days after the solstice, when the day is longest in the Southern Hemisphere and shortest in the Northern Hemisphere. This is the driving factor for long-term mean irradiance trends, where much lower levels of total irradiance are observed in the Northern Hemisphere.
While the amount of irradiance available is based on the length of the day, long-term cloudiness patterns are also present in the data, which can be seen off the western coasts of South America, Africa and Australia. The subtropical latitudes of the Southern Hemisphere see more easterly winds as the subtropical ridge moves southward, keeping moisture offshore on the western coast and bringing more moisture and clouds to the eastern coasts.
This year, much of the eastern U.S. will receive below-average irradiance for the holidays as a low pressure system moving east will bring rain and snow to the entire continent. However, the system will likely not reach the northeastern US during the day, New England will have above average irradiation. A high pressure system following rain and snow will bring sunshine to the US Midwest and West Coast, with average to above average irradiance during the day.
Europe will experience more variations than the US compared to long-term averages. Low pressure systems in the North Sea will push westerly winds and moisture from the Atlantic across the British Isles, northern France and Germany. Further south, light winds and a high pressure system will keep skies clearer and sunnier than usual. It will feel like a typical December day, as the Mediterranean coast has relatively less cloudy winters than further north.
In the long-term average, the difference between Spain and the south of France stands out, since the Pyrenees mountain range protects the Iberian Peninsula from the humid and cold winds from the north.
Solcast produces these figures by globally monitoring clouds and aerosols with a resolution of 1-2 km, 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 more than 300 companies managing more than 150 GW of solar assets worldwide. |
