The difference is around a factor of two between the US Southwest deserts and the German north sea coast [1]. So tracking installed peak capacity is not an idea

The difference is around a factor of two between the US Southwest deserts and the German north sea coast [1]. So tracking installed peak capacity is not an ideal metric, but it is very simple and gets the order of magnitude right. [1] https://globalsolaratlas.info https://globalsolaratlas.info