Christopher Mims, writing for Quartz:
You’d think it would be easy: the sun is “up,” and, like leaves and basking reptiles, solar panels should face in that general direction. But most installers of solar panels, especially the ones for homes, follow conventional wisdom handed down from architects, which holds that in the northern hemisphere, windows and solar panels should face south.
This makes intuitive sense since it would seem to maximize the amount of sunlight a panel will get as the sun tracks from one horizon to the other. But it isn’t true, at least according to a single study of homes in Austin, Texas. The Pecan Street Research Institute found that homeowners who aimed their panels toward the west, instead of the south, generated 2% more electricity over the course of a day.