I have a wall of windows, with my working wall on the opposite side of the room. I sometimes have projects on the wall for months while I think and rethink, move bits around, and ponder.
That said, take a strong colored piece of fabric, cut two decent sized pieces, and take one to the window. check it against the 2nd piece once a month for a year. Then you'll know. We can't say, in your situation because age of windows can have much to do with the results. I doubt with my new windows there will be any fading in my house, but the wall of 40 year old windows in my liviing room caused my carpet on that side of the room to fade. .. over 25 years.