I have a northerly wall on my house that doesn't get any sunlight to speak of. In the winter, sidewalk ice can last for months and the downspouts freeze. The sun really helps out in clearing the ice, even in the coldest weather. Is it possible to use a metal mirror, mounted on a telephone pole about 40 feet away, to reflect some heat into the area? Security mirrors are typically convex, so I don't think they would work.