Never seen that effect before over there. However I did once utilise the sun when it was opposite my window, hitting loch and bouncing into my lounge. It illuminated one of a number of portraits I happened to be doing at the time well back from the window.
When I checked my last picture of the light on Attadale it was 20:08, at 20:11 it was first of the rainbow, which shows how quickly it changed. I walked into the kitchen remembered the window was still open and went back to a totally different scene!
Yes, I had advantage of height and more to the right than your view.