I was thinking that in Canada the sun angle is so low in the winter that you could put solar panels on the southside of your house too, for when you needed power the most, in the dead of winter. They wouldn't even get snow on them and would be largely shaded in the summer. Solar panels are getting cheap and installing them on the side of a house should be cheaper than the roof. The sun might be shining in January, but the 6" of snow on yer roof solar isn't helping at all and neither is the low sun angle, but the ones on the southside of the house are doing just fine. Prices for solar panels continue to drop and as they get lower perhaps more people in the north will use near vertical ones in the winter attached to the south side of houses or buildings. They won't be needed or used much in the summer with long days and high sun angles. The falling price of panels might make this feasible.