John,
It's hard to imagine how the bolt could work it's way out with all that
weight on it but obviously it did. I have ~40-50 DPW TPMs in the field (since
late '90s) and have not had a failure of any kind other than snow and that was
pretty easily repairable.
I just finished installing 2, 16 SW270's TPMs and if you don't already
know, they are now being shipped with a jamnut. Maybe jamnut with loctite is
the way.
Bill
Feather River Solar Electric
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849 / 6544 fax
----- Original Message -----
From: john
To: [email protected]
Sent: Tuesday, April 22, 2014 6:52 PM
Subject: Re: [RE-wrenches] wrenches] Solar World shattered module
Dave,
I just had my first ever failure of a DPW TPM-8 with 8 SolarWorld 260's
on it. I installed it late last fall and the customer called last week to say
that it is on the ground. It turned out that the nut on the main pivot bolt
worked its way off, the bolt then worked its way out of one of the ears and
then the other ear bent 90 degrees and let the bolt slide out. The whole rack
then fell to the ground snapping the adjusting bar off. The rack landed face
down and the corner panel broke from hitting the ground first and two more both
hit the concrete base and broke. The other five panels were OK and the rack
parts are all OK except for the adjusting arm and the cap. The main bolt holes
in the strong-back are a little roughed up. We had torqued the main bolt
when we installed it and then the customer adjusted it to spring angle a few
weeks ago. He said he didn't touch the main bolt. The only thing we noticed
on these current racks was the appearance of never-seize on the main bolt. I
would suggest that everyone in windy areas should check the bolt torque often.
I have been told by notable mechanical engineers that the only way to assure
that the nut does not loosen is to use lock-tite. We used nyloks on all the
racks we built in 2009 - 2011. We started buying DPW racks again when we
discovered that shipping was cheaper than renting space for a rack shop.
PS Dave, Plan on coming to SolarFest 2014. It's the 20th anniversary
year and we are going to celebrate the good old days of solar. (as well as the
latest and greatest. I still remember when I was the Newbee. Any other
wrenches, I can get you free tickets (worth $75) contact me off-list.
John Blittersdorf
Central Vermont Solar & Wind.
email [email protected]
-----Original Message-----
From: Dave Palumbo <[email protected]>
To: 'RE-wrenches' <[email protected]>
Sent: Mon, Apr 21, 2014 6:32 pm
Subject: Re: [RE-wrenches] Solar World shattered module
Wrenches,
I have a customer with one SW 230 poly V2.0 frame (top mount) module that has
shattered glass. It is on a DPW TPM10 pole mount. She noticed it the other day
and does not think that it was hit by anything. I agree that is unlikely based
on the site conditions.
Other than by a falling tree, thrown rock, or twisted frame – is there
another way that glass shatters on a 65 degree tilted pole mount like this? We
installed the system 2 years ago. The module was on the lower corner of the
array.
· Is it likely that this modules frame was being pressured by the
module(s) above it? TPM has two rows of 5 modules in landscape, so this bottom
module has 4 modules mounted above it. Again it is a top mounted DPW pole array.
· Or, is there another way that glass shatters on this type of module?
I have not visited the site yet, just received the phone call today.
David Palumbo
Independent Power LLC
462 Solar Way Drive
Hyde Park, VT 05655
(802) 888-7194
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