[RE-wrenches] MT Solar / Iron Ridge Issue

Mon Jan 23 13:33:57 PST 2017

I whole heartedly agree with Gary!

Having been on the site (but not responsible for the install) I looked at
the carnage with an eye toward either installation error or equipment
shortfall. I could see nothing that indicated either and was amazed at the
failure. There were no trees down, no visible other wind damage, just
trashed equipment from clearly a very powerful, likely narrow, wind burst.
I've never seen IronRidge fail before like this either, having used it now
for several years. I've only used MT a couple of times, but have been
impressed with the smart and robust design.

Thank you Travis for supporting Eric in specific and Wrenches in general!

Howie
Howie Michaelson
NABCEP Certified Solar PV Installer™

Sun Catcher
Renewable Energy Systems Sales and Service
VT Solar Electric Incentive Partner
802-272-0004

On Jan 23, 2017 4:14 PM, "Gary Willett" <Gary at icarussolarservices.com>
wrote:

TRAVIS:

I have nothing technical to add.

However, I am very impressed that your company stood up, took ownership of
the issue, responsibility for the solution, and the good sense and humility
to ask for advice. That is so rare in today's world!

Best regards to you and your company!
Gary Willett PE
Icarus Engineering LLC
Irving TX

On 1/23/17 12:26 PM, Travis Jordan wrote:

One of our customers installed 3 of our MT Solar TOP15 pole mounts for his
off-grid customer in Vermont this last fall. During a recent severe wind
storm 4 modules blew off of the middle array. Two of the mounts also turned
on their poles. As the manufacturer of the pole mount we have identified
several issues but we are looking for feedback and any
information/recommendations from other installers to future proof our
design. This thread dovetails with the recent thread about the back-mount
module failure, but in this case the modules didn't fail, the bolts just
pulled out of the rail! I am assuming that we had greatly in excess of the
normal wind speeds at the site, but we have no way of determining what they
actually were. Our many other pole mounts installed in Vermont were not
affected by the storm.

Here is the situation. The site has 3 independent pole mounts with (15)
SW285's on each mount and the mounts are separated by roughly 20'. The home
owner took the liberty of cranking the mounts all the way to 90 degree tilt
for winter to eliminate snow build up. The modules that blew out were not
all adjacent to each other. The top two on the left and then two in the
middle are the ones that blew out, and they were all on the middle array.
The end clamps were still in position and did not fail. Both the end array
and the middle array turned on the pole, but the other end array neither
moved nor showed any adverse affects at all. The modules that blew off
ended up 20' BEHIND the middle array (to the North), and the installer
determined that the array did NOT turn clear around since the wires were
not pulled out. We are not sure how the modules got behind the array...

Regarding the rail failure:
The pictures show the rails were not bent but the T bolts had pulled clear
out of the top slot of the Iron Ridge rail. Iron Ridge only specifies data
for up to 45 degree tilt (not 90 degree), so we assumed responsibility for
the rail failure and paid for the 12 modules that were scratched or damaged
including the 4 that blew out, but now we are looking for a long term
solution. We are changing our manuals to say max 60 degree tilt (is that
acceptable to you installers?), and we are looking for a different rail
manufacturer than Iron Ridge. We are considering switching to S-Flex so we
can get away from the T bolt concept, but we are open to other suggestions?
Has anyone else had issues with Iron Ridge clamps failing?

Regarding the pole mount turning:
The engineers specified two set bolts, and we already had three for a
margin of safety. To determine where we are starting from we mounted the
pole cap on a jig in the shop press and applied 10,000 ft/lbs of rotational
force before the pole cap turned. After changing the back plate design we
were able to get that to 15,000 ft/lbs. Adding a 3/8" bolt clear through
the pole adds an additional 5,000 ft/lbs of capacity so we are adding a
hole in the pole cap for that as well. This puts us at double of what we
had, but we are reaching out to see if anyone has more actual data from the
field to add to the mix since we are already above and beyond engineering
data. We are also re-visiting the topic with another engineering firm to
determine if they have any additional data. We have also agreed to
compensate the installer for his time to repair the system, whatever he
chooses to invoice us for. As soon as this issue is resolved we plan to
provide a kit to modify all of our 15 module and bigger mounts that are
already installed to insure this does not happen again!

Eric, if you have any additional info or corrections to add as the
installer please chime in!

Looking forward to any questions, comments, or feedback any of you have!

Thanks in advance,

Travis Jordan
travis at jordansolar.net
travis at mtsolar.us
Direct: 406-206-5105 <(406)%20206-5105>

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