Hi Daryl;
I wonder if the DP&W rack is allowing some bending or torqueing of the
module frame, that over time with thin aluminum causes metal fatigue,
cracking, and finally total failure. Funny both of our isolated
failures involved the same rack. Also, I did more sluething and these
modules were the thinner (31 mm) 2.5 frame from Solarworld. They've
since gone back to a 33 mm frame; version 4.0. I also found in the specs
that the back pressure these modules can handle is 64 PSF, so I can't
believe we exceeded that. In dry, cold air at 9000 ft elevation, even
winds over 100 mph aren't half that pressure.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 1/10/2017 4:38 PM, penobscotso...@midmaine.com wrote:
Hi Ray,
I don't have much advice, but I can tell you that we have a couple of
ground mounted arrays at a local college (along the ocean) on the same
DPW high wind rated racks. The college chose to buy Chinese modules
from a competitor instead of my recommendation and one of the modules,
after about three years of being installed, gave way the same way,
literally ripping the washers and hardware through the thin aluminum
frame. I did tell them when I did the installation that they should
check every few years that all hardware was tight, as wind, over time,
vibrates the frame and I feel better when the client watches their
array for weak points. It is possible over time that the hardware
worked free a bit and allowed the wind to do what it did. Not sure, but
I've only seen it this one time in 29 years. We always torque our
hardware to DPW specs.
Daryl
Greetings All;
I just had the dreaded call from one of my higher profile commercial
clients: a remote radio repeater station had modules ripped off the
frame by high winds.
Two SW285s were damaged. The wind was strong enough to rip right
through the aluminum side rails. We had used the proper stainless 1/4"
bolt hardware with washers on the inside, etc. All the hardware was
still tight, it just tore the aluminum past the washers. This is not a
top down clamp system, but uses bolts through the mounting holes on the
back of the module. This was all on a DP&W rack with high wind option.
In 20 years in business, I've never seen that happen. Is there a
contact at Solar World? I'm not getting through on the tech support
line I have.
First, I need to know what the wind rating is on the modules blowing
from the back side, and
Second, a suggested fix for the remaining modules.
One module was completely ripped from the frame and thrown 30 yds (total
destruction), a 2nd one has cracks in the Aluminum, but has not let go
yet. I was thinking of adding some angle aluminum on the inside to beef
it up. IMHO, the frames are pretty thin aluminum compared to older
modules. I'll share some pics when available.
As always thanks in advance for your comments,
--
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
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