Three views from Global Solar Atlas data · switch with the buttons. Hover any city or country for its real 12-month curve.
Worst monthly PVOUT divided by the best month's. Range 0–1: low = winter collapses; high = flat year-round.
Seasonality index
Welcome to the Solar Seasonality Index
This map shows how much solar output swings between summer and winter across the world, built from Global Solar Atlas data.
Switch between the three views with the buttons. Hover or tap any city for its real 12-month curve, or any country for its area-weighted average. The dropdowns let you jump straight to one.
The big picture: for most of the world, seasonality is a smaller problem than it looks. In roughly two-thirds of places, oversizing the solar array by about +50% (1.5×) lifts even the worst month up to the yearly average. The stubborn exceptions sit in the far north, like Iceland, Scandinavia, northern Russia and Canada, where the winter sun nearly disappears.
