Manually Specifying Racking for Roof Mounted Systems (Part 1)

    Solar roof racking
    Although there are a host of online tools to aid in the design and creation of a racking bill of materials (BOM), it is important to understand what is going on behind the scenes to check your work.


    Panels can be arranged in either portrait (longest side is vertical) or landscape (longest side is horizontal) position. Further, rails can be run either north/south (vertical) or east/west (horizontal). As such, the four permutations below are available:


    Panel/Rail Orientation:


    Portrait:Landscape Drawing.png
    Both the panel and racking can run in East/West or North/South orientations.


    The formula for determining the length of a particular row or column of panels is as follows (where x = number of panels in column/row):


    (x)(length OR width of panel, depending on portrait or landscape) + (x - 1)(space required for each mid clamp) + (2)(space required for each end clamp) = required length of row or column


    Clamp spacing:

    IronRidge: ¼” for mid clamps, 1.5” for end clamps

    Unirac: 1” for mid clamps, 1.5” for end clamps


    For example, to determine the space required for a single row of 10 Canadian Solar CS6P-265P panels (dimensions: 64.5 × 38.7 × 1.57 inches) in portrait orientation using IronRidge racking, the equation would look like:


    (10)(38.7”) + (10-1)(0.25”) + (2)(1.5”)

    = 387” + 2.25” + 3”

    = 392.25”


    The E/W width of the array is 392.25” (32.6875’) and the N/S length of the array is 64.5” (5.375’, equal to the length of the panel).


    With this information, we can determine the racking BOM for this array.

    4 years 1 month ago
    Written by
    Conor Walsh
    Support topic
    Solar panel
    Racking and mounting
    Roof mount
    Ground mount
    Support keywords
    racking layout
    roof racking
    l foot
    mid clamp
    end clamps