Why are solar photovoltaic panels always on the south (or north) side of the roof?
In order to get the maximum electrical output from photovoltaic panels they need to be oriented to solar south in the northern hemisphere and solar north in the southern hemisphere. Solar north and solar south are the same as magnetic or compass north or south. There is about a fifteen degree difference between them. Most solar photovoltaic panels are set at home latitude plus fifteen degrees or home latitude minus fifteen degrees. Depending on if you want a summer or winter bias to the angle of the solar panels. In higher latitudinal areas it makes more sense to have the photovoltaic panels set on a winter bias, so that during the winter the solar panels still get enough sun light to produce electricity.
