To generate most electricity, the location of solar panels should be such that the maximum amount of solar radiation reaches them. In the northern hemisphere, the optimum solar panel location is a south-facing roof.
Solar Panel Orientation
For best performance, you need around 100 square ft of unshaded south-facing space for every kilowatt of electricity. The amount of solar radiation will be less if your roof faces SE or SW.
The condition of your roof is important, too. Ensure the roof can hold the weight of the system (about 3-5lb per square foot) and that the roofing material will last as long as the PV system (25-30 years).
Try to avoid mounting PV panels in areas that receive shade from trees, electrical cables, buildings, chimneys, vents or any other source. Remember that shading in an area can change from summer to winter as the sun’s path changes. An installation professional can estimate the shading your system will receive.