[RE-wrenches] Attaching Array To or Through Ply
Ray Walters
ray at solarray.com
Thu Mar 30 18:44:27 PDT 2023
Hi Jason;
I was like you: thinking good ol' bottom mounting with SS hardware was
the best. All of us old wrenches were wrong.
The top down mounting system is much stronger. I've only had a handful
of failures over 25 years, and all were bottom mounted. The module
completely ripped off the rack, leaving the stainless hardware, washers,
etc with a thin sliver of module frame between. For repairs, I come
back and install 1/2" SS angle on the inside of the module frame to
spread the load more. AND....on new installs, no more bottom mounting.
If you compare today's modules with old 12v models from 20 years ago,
you'll see: much thinner metal on the bottom frames now.
Meanwhile I saw several systems survive Hurricane Maria in Puerto Rico:
all top down mounting. You are correct that the failures come from the
modules themselves letting go, not the racking. Either the wind itself
is so strong as to blow the glass, then the frame looses its structure,
or flying debris breaks the glass. There were some MW PV fields that got
tore up pretty bad. So no, ground mounts definitely can be destroyed.
They had tornadoes moving inside of the hurricane, and you could see it
in the damage, 50' wide strips of total carnage with undamaged modules a
few feet away. Like you said, The storm has a mind of its own.
As far as mid clamp T bolt failures, I can confirm that probably a
majority are not installed correctly, especially Unirac, which are
terrible to get the T lined up right. I've done numerous inspections
world wide, and a signifcant % of racking I looked at was NOT installed
correctly.
1) The Ts not squarely lined up with the rail,
2) massive over torqueing, to the point the bolt can't be reversed
3) under torqueing, to the point the modules had slipped down a little.
Most of these problems come from installing with an impact driver.
Impact drivers are a great tool (so is a hammer), but you got to know
when and where to Not use them, too. They're great for installing the
lags and L feet, but then get that tool off the roof.
Use an electric screw driver, socket wrench, or *drill with a clutch*
set low to snug up the clamps, and then final torque with a torque
wrench. Period.
Ray Walters
Remote Solar
Former NABCEP 2004-2016
On 3/30/2023 4:34 PM, Jason Szumlanski via RE-wrenches wrote:
> That would be great if it were possible! I'm not sure how you bottom
> mount a flush mount array. For a brief period many years ago, I was
> building solar trailers. I would bottom mount 4-6 panel arrays on
> rails in my warehouse and then hoist them up and through-bolt the
> whole array on the top of a trailer. I wasn't about to allow a trailer
> going 80 mph on the interstate to have panels mounted on the roof with
> mid-clamps! I had no idea what I was doing, but I had enough sense to
> know that would have been a bad idea!
>
> I did provide feedback to IronRidge regarding a handful of failures
> from Hurricane Ian, but most of the issues we saw were most likely
> related to catastrophic module failure. After all, they are only
> tested to 5600 Pa uplift for even the best options we have on the
> market and 2400 Pa for some (which I refuse to use). The mid-clamp
> T-bolts tearing out of the rail are slightly concerning, but this was
> pretty rare, and honestly it could be related to installation torque
> issues, misalignment, or coupled with module failure. There was no
> widespread or definitive reason for rail failures at the clamp locations.
>
> I would suggest that FEMA's recommendation is overkill and not based
> on much science, but conclusions based on anecdotal information
> without statistical data. It should be scrutinized. I think it would
> be a good idea to consider bottom mount for ground racks and tilt
> mounts that allow it, but it's just not practical or possible in the
> vast majority of residential installation cases. On that note, I am
> not aware of any ground mount failures around here from Hurricane Ian
> except for submerged arrays that were washed away from storm surge
> (Yikes!). And the handful of failures that we observed were a drop in
> the bucket relative to the installed numbers here.
>
> One other thing. Wind direction, upwind obstructions/windbreaks, and
> luck have a huge amount to do with failures (of both PV and roofs
> themselves). These storms pick winners and losers. You will have ten
> houses in a row with pool enclosures mangled, and one in the middle
> that is unscathed. It's crazy to see. We have lots of gated
> communities with houses close together. When wind accelerates between
> houses, it can topple air conditioning units and pool equipment. If
> you look hard enough at where the wind was coming from and the
> surrounding area, you can really see how there are so many factors
> that come into play.
>
> Jason Szumlanski
> Principal Solar Designer | Florida Solar Design Group
> NABCEP Certified Solar Professional (PVIP)
> Florida State Certified Solar Contractor CVC56956
>
>
> On Thu, Mar 30, 2023 at 7:35 AM Christopher Warfel via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
>
> If you look at FEMA's design guide for solar installations in FL
> and the Caribbean, the recommended module to rail attachment
> method is back to using the attachment holes in the solar module.
> Chris
>
> On 3/30/2023 5:56 AM, Jason Szumlanski via RE-wrenches wrote:
>> This thread has morphed into more than it started as, and for
>> good reason. I want to provide some practical/anecdotal
>> information, having just gone through arguably the most
>> catastrophic wind event in Florida's history (Ian) since the boom
>> in solar energy started, and another major wind event (Irrma)
>> just 5 years ago.
>>
>> First, Aside from the Sunmodo and Quickbolt decking-only
>> products, I would check out IronRidge's new entrant into the
>> market, the IronRidge HUG. If you can't find info on it, ask your
>> distributor or IronRidge sales rep. They have data on truss
>> attachments and also missed truss installation procedures. It's a
>> unique approach to a dual-purpose product, and they did
>> a stellar job on the engineering documentation in my opinion.
>>
>> Ok, now let's get to my most important point. Due to Hurricane
>> Ian, the number of roofing PV attachments that I have witnessed
>> that failed due to fastener pull-out (mine or competitors):
>>
>> ZERO
>>
>> The only building where we had any mounts fail was on a flat roof
>> with pitched panels and Anchor Products mounts on TPO membrane,
>> but the mounts themselves did not cause the failure. The roofing
>> system itself failed, causing a small section of the PV system to
>> fail. But even in that case, the following applies...
>>
>> The weak point in a well-designed and installed system is not the
>> fastener or flashing system. The module to rail connection is
>> where we saw failures. These failures fell into a few categories:
>>
>> * Windborne debris struck panel, panel frame failed, panel
>> popped out of mid-clamps.
>> * Catastrophic wind forces popped panels out of mid-clamps (a
>> good percentage of panels found INTACT and still functional
>> on the ground!) I suspect the panels became covex in the
>> wind, bending frames inward.
>> * Windborne debris struck mounting system components, panel
>> dislodged, often still on the roof suspended by DC leads.
>> * Mid-clamp t-bolt tore out of aluminum rail channel (IronRidge
>> UFO, Unirac SM).
>> * Mid-clamp sheared off (Quick Mount QRail).
>> * Unexplained module detachment failures.
>>
>> On 9/28/22, while I stayed up all night bracing myself against my
>> front door that I thought was about to fail, I was imagining how
>> many roof leaks my clients were about to endure, and wondered
>> about the efficacy of my business going forward. Those fears
>> never materialized. Aside from a handful of minor panel
>> dislodgements, there was no panic following the storm (with
>> respect to solar panels). The bigger problem became all of the
>> people needing to remove panels for roof replacements, but PV
>> panels largely protected roofs in the areas where they were
>> installed. Sadly, the rest of the roof often did not fare as well.
>>
>> Anyway, back to the decking attachments. I have been skeptical of
>> non-flashed products for comp shingle roofs for a long time. My
>> thinking is coming around, particularly with the HUG (I trust
>> IronRidge's testing regime). And sealants have come so far. This
>> method will remain up for debate probably for a long time. Around
>> here, I am pretty certain these products will outlast the
>> shingles they are placed upon. We only get 15 years out of most
>> shingle roofs around here.
>>
>> About the pull-out fears... Mine are gone. We have done many flat
>> roofs with long fasteners through steel decking or wood decking.
>> These screws are usually something like #15 XHD screws in lengths
>> from 5 - 12". Not a single failure. We have also used Quick Mount
>> QBase Low-Slope bases on pitched tile roofs that were only
>> screwed into decking with 4 fasteners each (due to horizontal
>> truss transitions) in some cases. Zero failures. But the most
>> relevant attachments I can think of that are germane to this
>> discussion are the many thousands of S-5 SolarFoot that we have
>> screwed into decking on 5V metal roofs around here. These have
>> four screws per attachment, and S-5 load tests show something
>> like 240 lbs of pull-out strength in OSB (adjusted for safety
>> factor). When engineered for our wind loads, we usually get
>> anywhere from 36-48 inch attachment spacing, sometimes 24 inches
>> in certain roof zones. Again, not a single failure.
>>
>> I have more solar installations on Sanibel Island and Fort Myers
>> Beach (Hurricane Ian Ground zero) than anyone. Many of those have
>> decking-only attachments, S-5 clamps, flat roofs, or other
>> attachments other than trusses. I can tell you unequivocally that
>> I trust decking-only attachments from a pull-out strength
>> standpoint. When properly engineered, with cautious attachment
>> spacing, these mounts work in both OSB and plywood. Because of
>> the inconsistencies in OSB, we always err on the side of caution,
>> if not in the engineering, then in the installation, by
>> installing more attachments than prescribed. But the evidence is
>> clear. It works.
>>
>>
>> Caveat to the above: I have zero experience with snow or seismic,
>> and no experience on roofs exceeding 8:12 pitch, and few above 6:12.
>>
>> And one more shout-out to S-5 clamps on standing seam roofs.
>> Aside from one minor failure of the roof metal itself, not an S-5
>> failure, we had zero failures of S-5 clamps attachments to report.
>>
>> I hope this anecdotal information helps and sets some fears
>> aside. Please reach out to me off-list if you want any specifics
>> or details about our experience with catastrophic wind events.
>>
>> Sincerely,
>>
>> Jason Szumlanski
>> Principal Solar Designer | Florida Solar Design Group
>> NABCEP Certified Solar Professional (PVIP)
>> Florida State Certified Solar Contractor CVC56956
>>
>>
>> On Thu, Mar 30, 2023 at 2:47 AM William Miller via RE-wrenches
>> <re-wrenches at lists.re-wrenches.org> wrote:
>>
>> Friends:
>>
>> Thanks for bringing up this scenario.
>>
>> I have two problems with using a product such as the
>> easy-feet or other deck-fastened brackets, particularly on a
>> rigid foam-above-sheeting roof:
>>
>> 1.I worry about compression of the foam material over time.
>> This could leave a void under the bracket which could lead to
>> leaks or wobbly brackets.
>>
>> 2.I don’t believe in chemical solutions for sloped-roof
>> rain-proofing. By that I mean the use of caulks, gaskets,
>> etc. Since roofs were first thatched, the overriding wisdom
>> is that gravity is the only way to reliably shed water.
>> Overlapping, seamless material is the only method to use.
>> Caulks degrade, roof surfaces become powdery, and the rafter
>> is often under an architectural feature or seam in the shingles.
>>
>> I researched the PLP EZ foot back when the company was DPW.
>> The fasteners provided were not rated for the application,
>> according to the fastener manufacturer. If you can match the
>> fasteners to the decking and the forces, then maybe you have
>> a start to a mounting solution.
>>
>> Whatever product you use, I would install it on a section of
>> flashing metal, lapped under the next course up. The
>> flashing gives a flat, seamless surface to caulk or gasket
>> to. The thicker and wider the flashing, the more you
>> distribute the downward force
>>
>> applied to the bracket by weight and fasteners. Any voids
>> under the bracket will have an overlapped flashing above it.
>>
>> I hope these musings help you find a solution.
>>
>> William Miller
>>
>> PS: I have encountered this roof configuration a few times on
>> flat, built-up roofing (BUR
>> <https://homeinspectioninsider.com/built-up-roofing/>). We
>> have dealt with it by cutting through the foam, installing
>> blocking on top of the sheeting and having a roofer feather
>> the blocks into the roofing with cant strips
>> <https://www.blueridgefiberboard.com/cant-strip-tapered-edge-smoothes-roof-drainage-slope/>.
>> A pitched roof is a different situation, however.
>>
>> Wm
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com <http://www.millersolar.com/>
>>
>> CA Lic. 773985
>>
>> *From:*RE-wrenches
>> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On Behalf
>> Of *August Goers via RE-wrenches
>> *Sent:* Wednesday, March 29, 2023 11:47 AM
>> *To:* RE-wrenches
>> *Cc:* August Goers
>> *Subject:* Re: [RE-wrenches] Attaching Array To or Through Ply
>>
>> We've found that in the Bay Area that deck-mount solutions
>> typically pencil out structurally (via a structural
>> professional engineer) as long as the deck is 1/2" plywood or
>> thicker, assuming we have all the info on how the roof is
>> constructed. The big assumption is that we can get all that
>> roof construction info, which can be difficult for existing
>> structures.
>>
>> We haven't taken the plunge yet on the flahingless deck mount
>> products like the Sunmodo Nanomount or Unirac Flashloc Duo. I
>> do think that they offer several significant advantages
>> including not needing to find rafters, thus virtually
>> eliminating missed pilot holes, and not disturbing the comp
>> shingle by eliminating prying up the courses to insert the
>> flashing.
>>
>> August
>>
>> Luminalt
>>
>> On Wed, Mar 29, 2023 at 11:34 AM Solar Energy Solutions via
>> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>>
>> We like Spider Rax… with the flashing!
>>
>> *Spider-Rax PV Solar Mounting <https://spiderrax.com/>*
>>
>> *spiderrax.com <https://spiderrax.com/>*
>>
>>
>>
>> *Error! Filename not specified.* <https://spiderrax.com/>
>>
>> *Andrew Koyaanisqatsi*
>>
>> President
>>
>> *Solar Energy Solutions, Inc.
>> /The BRIGHT CHOICE/*
>>
>> *Since 1987, helping you and your *
>>
>> *Portland neighbors move towards an environmentally
>> sustainable future.*
>>
>> *503-238-4502 <tel:503-238-4502>
>> www.SolarEnergyOregon.com
>> <http://www.solarenergyoregon.com/>*
>>
>>
>>
>> On Mar 29, 2023, at 11:04 AM, Jerry Shafer via
>> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>>
>>
>>
>> Wrenches
>>
>> Sounds like a SIP's type product, there are quite a
>> few multi hole attachment bases that are designed for
>> SIP's. Most will have a larger base, lots of holes
>> for screws to attach that do not require rafters
>> underneath to attach.
>>
>> Fun times
>>
>> On Wed, Mar 29, 2023, 8:30 AM frenergy via
>> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>>
>> Matt,
>>
>> I guess my questions are 1/2" plywood
>> or 5/8" and how thick is the foam? Oh and I
>> assume its nominal 2X6 T&G? Do you know how the
>> plywood is attached?.....through the foam into
>> the T&G?... to stringers, nailers or whatever
>> they're called?
>>
>> Bill
>>
>> Feather River Solar Electric
>>
>> Bill Battagin, Owner
>>
>> 4291 Nelson St.(shipping)
>>
>> 5575 Genesee Rd. (USPS, UPS)
>>
>> Taylorsville, CA 95983
>>
>> 530.284.1925 Office/ 530.258.1641 Cell
>>
>> CA Lic 874049
>>
>> Solar powered since 1982
>>
>> On 3/29/2023 7:53 AM, Dave Tedeyan via
>> RE-wrenches wrote:
>>
>> Hi Matt,
>>
>> I've used these in the past when on a comp
>> roof and there was no good way to get into
>> the rafters (or TJI's in this case)
>>
>> https://sunmodo.com/nanomount/
>>
>> You might want to replace the screws with
>> something shorter and beefier though to get
>> more grip if you are only going into 1/2"
>> plywood.
>>
>> Cheers,
>>
>> Dave
>>
>> On Wed, Mar 29, 2023 at 10:38 AM Matt Sherald
>> via RE-wrenches
>> <re-wrenches at lists.re-wrenches.org> wrote:
>>
>> Hi All,
>>
>> I've run into a roof-mounted job where
>> the roof is built-up with the following:
>>
>> Comp shingle
>>
>> Plywood
>>
>> Foam board
>>
>> T&G (roof deck, but also interior ceiling)
>>
>> The beams that hold the t&g up are
>> wide-spaced and not convenient for
>> fastening the full extent of the array.
>>
>> This being the case, I was considering
>> other fastening options and am writing to
>> pick the collective brain of the Wrenches
>> to see how others have addressed similar
>> situations.
>>
>> One thought I had was to use the PLP Easy
>> Mounting Foot and I'd be glad for any
>> opinions on that or another solution.
>>
>> -Matt
>>
>>
>> --
>>
>> Matt Sherald
>>
>> PIMBY Energy, LLC
>>
>> 304-704-5943
>>
>>
>>
>> _______________________________________________
>> List sponsored by Redwood Alliance
>>
>>
>>
>> _______________________________________________
>>
> --
> Christopher Warfel
> ENTECH Engineering, Inc.
> PO Box 871, Block Island, RI 02807
> 401-466-8978
> <http://entech-engineering.com>
>
>
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