Place a level flat against the roof surface. That number is your slope ratio — for example, a 4-inch rise = 4:12 pitch (~18. Roof pitch, also known as roof slope, refers to the steepness or angle of your roof. Convert rise/run to degrees, check material compatibility, calculate rafter length. Get roof pitch ratio, angle in degrees, rafter multiplier, and the optimal solar panel tilt angle for maximum. A general rule is to match your roof slope to your latitude for the most balanced annual solar output. If you're curious about your roof's pitch, you can measure it yourself with a simple method.
