Do Solar Panels Work on Shaded Roofs?

By Sarah Lozanova, Solar Energy Writer

Many homeowners want to install a solar electric system but don’t know if their roof gets enough sunshine. The return on investment from the solar panels and the positive environmental benefits are highly dependent on the energy production.

Here’s the essential information to determine if a house has ample solar potential.

​Roof Orientation
Solar energy systems generate the most electricity when the panels are pointed south. If the orientation of the roof is slightly off from due south, it won’t have a dramatic impact on the total energy production.
If the solar panels face east, they will generate more energy in the morning. Conversely, if the panels face west, the system will have excellent afternoon production but little in the morning. It is not recommended to install panels on a north-facing roof (in the northern hemisphere).

To determine the energy loss due to orientation, go to the PVWatts website and edit the azimuth field.

Shade from Trees and Buildings
Although trees are wonderful, they can have a negative impact on solar production. Buildings and trees located east, west, and especially south can hinder electricity output. The most crucial window is the mid-day hours, between 9 am and 3 pm. Thus, obstructions on the south side of the home can have the biggest impact. If trees are an issue, trimming certain branches might be highly beneficial.

Evergreen trees can have the biggest impact on solar panels because they create shading throughout the year. Deciduous trees tend to not have leaves when the sun is lower in the sky during the cold weather months. When planting new trees, select shorter varieties or plant them on the north side of the home.

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Image Credit: Sundog Solar

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Do solar panels work on shaded roofs?