[RE-wrenches] Module Racking Attachment to SIP Roof

[penobscotsolar at midmaine.com]

Hi Gary,
  We've done several SIP projects and I've done the same research you are
now likely doing.
  What I ended up designing was a system of aluminum plates (8"x8") that
screwed into the roof sheathing at four points with 1/4" ss lag screws,
then using 1/2 threaded rod that ran through the center of the plate
through the SIP to a similar plate mounted on the inside. We used
bituthane between the plate and the roof, as well as silicone, then used
standard racking with flashing. The oldest SIP job we have is now going
on seven years with no problems at all.
   Feel free to contact me off list if you have any questions about this.

Daryl DeJoy
NABCEP Certified PV installer
Penobscot Solar Design





> Fellow Wrenches:
>
> Working on a residential PV design using Structural Insulated Panels, or
> SIP panels. Preliminary design is three AC strings of 17 microinverters,
> in three portrait rows ~18" apart.
>
> The good news is that the builder wants to include the PV as part of the
> original construction.
>
> The wood structural roof beams on which the SIPs will rest are on 20
> foot centers, and run the same direction as the portrait PV modules. The
> SIPs are 10-1/4" thick, with 5/8" plywood on top and bottom. Roof pitch
> is 1.5:12 (low pitch).
>
> Are there any PV rack mounts specifically designed for a SIP structure?
> I've done a lot of web searches, and can find no specific products.
>
> I've looked at the Eco-Fasten^(TM) Universal Roof Attachment Bracket. It
> has 8 mounting holes per attachment point using #14 screws. Pull-out
> resistance will be low per attachment point with 5/8" plywood.
>
> One solution could be a product that had a bolt-plate on the bottom of
> the SIP, that penetrates the SIP with long 5/16" threaded bolt(s), and
> then attaching to the PV mount at the top of the SIP. The UniRac
> SolarMount steel flat-top mount has four 5/16" bolt-holes and might be a
> good choice. This method should have no problem achieving the required
> pull-out resistance.
>
> Any suggestions, installation experience, on how to put PV on a SIP roof?
>
> --
>
> Regards,
>
>
> Gary Willett, PE
> Icarus Engineering / Solar Services LLC
> NABCEP Certified Solar PV Installer # 031310-246
> Gary at IcarusSolarServices.com <mailto:Gary at IcarusSolarServices.com>
>
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