> They do not avoid it "as much as possible". The panels are shading each other in that very photo

You haven't linked the photo…

> It's basic trigonometry. Narrow spacing needs the sun to get pretty high before shading stops.

Of course it's “basic trigonometry”… It doesn't matter if the panels are shaded when the incidence angle is high anyway!

> The limiter is the price of land. If land was free I guarantee they would spread them out more.

They wouldn't, they'd just put more panels on a bigger surface. And again, industrial actors are maximizing the economic output they can make. Whatever decision you take at your level, it's going to be more expensive than what they are doing, and more efficient.

> No it's not! If you need it for most of the year it's not "over"

Yes it is… By definition you are over-paneling if your peak production is higher than what you use. This threshold is important because cost calculations only works when you haven't reached that yet!

> If you need 5x or more for half the year, you calculated "x" wrong. Your math is what's nonsense here.

X is the value for which the cost/MWh makes sense. The further you got from there, the bigger fraction of the power is unexploited and the higher the cost per unit of useful electricity rises.

I didn't invent these concepts or these calculations, those are standards when talking about solar.