Sun analysis on SketchUp import

After several attempts I keep failing to perform a sun analysis in Rhino on an imported file from Google SketchUp in order to calculate the direct sun hours.

In Grasshopper I created the following flowchart.
But this flowchart requires a brep-input to perform a proper sun hours analysis.
For some reason I can’t select the SketchUp imports as a brep.
So I tried to select it as a mesh and convert the mesh into a brep. This is shown in the second part of this screenshot:

However performing a sun analysis with a mesh gives unrealistic results, regardless if I alter the grid size.
Does somebody have an idea how I could perform a proper sun analysis on an import from Google SketchUp?

I have done some research in the mean time and found these 2 links:

However these methods apply to former versions of Rhino and Ladybug.
I’m using Rhino 8 and Ladybug 1.7.0. Does anybody know how I can perform a direct sun hour calculation on an imported file from Google SketchUp?