[schiffern]

I'm also a fan of vertical panels in snowy regions, but at the same time it kinda dodges the question.

In a non-snow region (which is most of the country, a fraction which is only increasing decade by decade), what is the optimal tilt angle? 70°? 80°? More? This is quite important for large solar panel farms in the hot and sunny South/Southwest.

The cosine loss is easy to model, so to answer the question what we need is a curve that describes how the convection cooling effect varies with angle.