https://www.pveducation.org/pvcdrom/properties-of-sunlight/making-use-of-tmy-data#footnote1_4a2atu6

According to this model and TMY3, solar radiation on a building wall facing south is sometimes negative. Is it reasonable?

https://www.pveducation.org/pvcdrom/properties-of-sunlight/making-use-of-tmy-data#footnote1_4a2atu6

According to this model and TMY3, solar radiation on a building wall facing south is sometimes negative. Is it reasonable?