SketchUp does not provide for reflections on surfaces other than from a defined light source. Technically that would be complex.
Reflections in exterior windows cause problems, especially if they appear strongly in the source photographs.
- They may include reflected images of unwanted objects and scenes, e.g. adjoining buildings, trees and skylines.
- They do not vary as the viewing angle changes up, down and sideways.
- They may prevent you copying sections of glazing from one part of a building to others.
Here’s an article that addresses reflection in terms of the appearance of glass surfaces: Painting light: exterior glass.