Solar insolation is a measure of how much sunlight is available at any particular location.

The rotation of the Earth around its axis is setting the diurnal daylight cycle. The rotation of the Earth around the Sun is causing an annual variations in daily possible sunlight hours due to the declination of the Earth's axis. Atmospheric processes like humidity circulation in the form of clouds etc are causing scattering and reflecting of the sunlight when passing through the atmosphere which does decrease the amount of energy which reaches the Earth's surface. Solar insolation is not uniform around the Earth therefore, but rather very dependent on the climatic conditions at a particular location.

Solar insolation is an important measure to understand weather and climate pattern as well as local plant growth pattern around the world. Is is also of particular importance for estimating the viability of energy production through solar panels at particular locations.

The Clouds and the Earth's Radiant Energy System (CERES) project provides satellite-based observations of Earth's radiation budget and clouds. It uses measurements from CERES instruments flying on several satellites along with data from many other instruments to generate a gridded solar insolation dataset, among other products.

The location loc can be specified as latitude and longitude {lat, lon}, GeoPosition[...], or as a named entity Entity[...].

For a specific location, AverageAnnualSolarInsolation returns by default a Quantity corresponding to the closest point in the underlying dataset.

The spatial resolution of the gridded dataset is 0.25° x 0.25°.