Analysis of solar water heat panels on Bldg 404 roof: Figure 1 shows the arrangement of the solar panels on the existing roof. This arrangement is based on the use of panels with a dimension of approximately 10’ long by 4’ high. These dimensions are taken from the “SolarHot” manufacturer’s data (see Figure 3). Figure 2 shows the panels with respect to the roof structure. The existing open web steel roof joists are spaced at 10 feet on center. Although some of the panels will fall directly over a joist, some of them will not. This will require the use of added structural supports between the existing roof joists. Figure 4 shows the optimum angle for the panels. The optimum direction would be to have the panels facing due south. However, it has been decided that the panels shall run with the slope of the roof. As such, the angle of the panel must be increase to 69 degrees from horizontal to offset the slope of the roof and the direction the panels faces with respect to south. Figure 5 is an excerpt from a publication which explains the snow drifting effect around solar panels on a roof. In order to facilitate analysis of the structure, a simplified diagram of the snow drift shall be used. It should be noted that the diagram from the excerpt only accounts for drifting from one direction. Since the worst case scenario would be to assume drift accumulation due to wind from either direction, this shall be the load case used for this analysis. Figure 6 shows the shadowing effect of one panel against another panel. It is based on the solar angle on 21 December at 1200 hours. Figure 7 illustrates the snow drift as a combined drift due to blowing snow from both directions. In actuality, the drift from the left is snow blowing perpendicular to the panels and being deposited against the windward side of the panel. The drifting from the right is actually snow being transported from the other side of the gable roof and blowing at an angle to the panel, depositing snow at the back of the panel. The drift load would be added to the balanced snow load. It is assumed that the drift accumulation will eventually reach the top of the panels but not exceed them.

N Figure 1

Figure 2 Solar panels Structural support members added between joists N 76’-9” 71’-9” Ridge line

Figure 3

64 degrees Angle of panel = (Latitude x 0.9) + 30 = (38 x 0.9) + 30 = 64 degrees Figure 4

(Excerpt from “Loads Due To Drifted Snow” by J.T. Templin and W.R. Schriever from the National Research Council Canada August 1982) Figure 5

64d 27d 6.67’ Shadow zone on 21 December at 1200 hrs 4.00’ Balanced Snow Drift Snow From Left Drift Snow From Right Wind from right Wind from left SOLAR SHADOW EFFECT SNOW LOADING CONDITIONS Figure 7 Figure 6