[RE-wrenches] PV wind load

[Rebecca Lundberg]

Solar is somewhat 'new technology' where I live. :-) I have a building
inspector that feels that (32) Sanyo modules (6.88 kW array) mounted to a
house roof is going to cause undue stress to the roof truss (it is a regular
house in a Minnesota suburb, building height is 26', 30 degree roof angle,
in a suburban neighborhood. 2" x 4" manufactured truss). We are leaving
12-24" on each edge with no PV, and are careful to attach to the center of
each rafter.

The inspector is not that concerned with dead load, but is especially
concerned with wind load. We have provided an engineering letter that
ascertains that a solar array mounted parallel to the roof surface is well
within the parameters of what a typical roof truss can handle. We were
required to have an engineer look at this address specifically, so we then
provided an additional engineer's letter that affirmed that yes, solar
mounted in the manner we proposed (with Quick-Mount attachment and Unirac
SolarMount rails, all installed according to manufacturers' instructions)
would be fine on this home. The building inspector insists that the wind
load is excessive, and wants more analysis. Do any of you have ideas,
experience, or data that might help me?

Rebecca Lundberg
Powerfully Green
Champlin, MN
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