To this day, I also don't know the correct key to solving this one. At this point I also don't care :P

I eventually figured it out, but it's been so long I don't remember the solution :(

I wasn't able to find any way of finding the right position for this one either, and assuming this uses the same glare mechanic as the other puzzles in this area I'd be unable to continue without. would be nice to have some pointers of how I might figure out the solution myself after all, that'd be much more satisfactory than just the solution

I did finally get this at some point, but I had to read someone else's guide I think.

I have the same problem. I cannot find an angle that sheds glare on the left 1/3 of the panel. It is in shadow, so there is no angle that even allows light to fall on it, and there appears to be no way to move the obstacles. Unfortunately this shot shows the solution but not how you find it.