هل تتطلب المصابيح الشمسية ضوء الشمس المباشر لتعمل أم أن الضوء غير المباشر كافي?

I live in America and I find some blue LED street lights. I don’t understand the purpose of setting these lights. Why do they make the light blue?

The street lights always light up at the same time. But if one breaks down, the others will still work. Then what kind of circuit is this, series or parallel?

I think turning street lights on for the whole night is a waste of energy. In the late night, there will be few vehicles and pedestrians. Why can’t we turn off the light at night?