How to calculate wind pressure over a tilted Solar Panel

[Chemical96]

thread507-219092

For the calculation of wind pressure, I have seen that some engineers averages the values from Figure 6-18A (ASCE7-05 ) for the calculation of Cn values. For example if you have a solar panel or a solar thermal plate with 15 degrees and no obstruction, the cnw and cnl for gamma =0 are as follows:

-0.9, -1.3 Average = -1.2
-1.9,0 Average = -0.95

Why will they average ???? ...It will be better to pick the worse scenario, cn = -1.9 ...right ??? Will any body agree on this ?



Thanks

 

[Teguci]

If you use the average pressure coefficient (the average of the two) times the area, you will get the full wind vector that will need to be designed for. The only thing being neglected is the eccentricity caused by the unbalanced condition.

 

[Chemical96]

Very good response. If I average..then I will use -1.2 since it is a larger value (Load Case A).

Thanks