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Sunlight is the fuel for all solar technologies, and the term solar resource refers to identifying how much of it is available in a given collector area. There are three main factors that affect a roof’s solar resource: the direction the roof is facing, shading, and roof pitch.
- Direction: Since we live in the northern hemisphere, the sun is always shining from the south. Thus, solar systems on a south facing roof, will receive a greater solar resource than roofs facing other directions. Southeast and southwest facing roofs will still receive a lot sun. East and west facing will receive less, but may still receive enough sun. Roofs that are north facing will not receive enough of solar resource to make installing a system make sense.
- Shading: The space for your solar panels should have direct access to the sun, with little to no shading most of the day (10 am to 3 pm). Common things that may affect sunlight exposure other buildings, trees, and sometime large chimneys.
- Pitch: Pitch refers to the angle of your roof. In Oregon, the ideal roof is between 20 and 35 degrees, though steeper and flatter roofs may still work.