I know its winter time. so we are all thinking heat . but i would like to share something. every summer we hang wood frames with solar blankets. emergency blankets, Mylar stretched tightly over them in front of our solar window this is a cheap and easy way to hide from the sun. hope this helps
Reflecting ponds are sometimes used this way, to capture low-angled winter light outdoors and throw it onward toward the windows/ceiling. You could also perch it over a skylight, pointing south, like a satellite dish.
But around here, we'd probably just roll them up to keep them safe from wind & weather; they might get damaged easily in storms, and we have more of those in the winter than sunlinght. So we rely on insulation and artificial heat, mostly.