For municipal street lighting, because the arc of the sun is primarily in the south, they are optimized/”calibrated” for north pointing. Over a year's time, the yields an average "on" time is ~10 hours/day.
Maybe it’s the opposite in the south hemisphere, and illegal on the equator?
Before cheap photoelectric controls, there were older-design time clocks available with “astronomic” dials; that automatically adjust as the days grow shorter or longer. When buying them, they had the instruction to Indicate City and State nearest installation when ordering.”
