How do we know if our roof is suitable?
Nationally, only about one quarter of roofs are suitable for solar panels.
To determine if your roof will work, we go through a process that can take several months, and includes evaluating:
Orientation: South-facing solar panels produce the most electricity over the course of the year. East/west-facing roofs produce a few percent less, making their payback time longer. Flat roofs work fine, north-facing roofs don’t.
Shading: Trees, chimneys or buildings on the south are going to be a problem. To the east or west, it will depend on their height and distance from the solar panels. Energy Trust of Oregon requires a minimum of 80% sun. Flat roofs with open space are fine.
Stucture: Solar panels generally weigh 3 – 5 pounds per square foot, so making sure your building structure can support that is essential. Most newer buildings are fine.
Roof age / condition: It’s generally preferable to install solar panels on roofs that won’t have to be replaced anytime soon. That’s because solar panels today carry performance guarantees of 25 years or more, and removing and replacing solar panels from most roofs is expensive. Energy Trust of Oregon requires at least 10 years of life left on a roof. Metal roofs, which are generally long-lasting, are ideal.