<div dir="auto">Hi Corey -</div><div dir="auto"><br></div><div dir="auto">For many years we used Pro Solar racking and Unirac Solarmount and tightened the clamps with impact drivers. At some point maybe roughly 8 years ago, Unirac switched its mid clamps to stainless steel self grounding clamps with teeth to bite into the module frame. We continued to use impacts with no issue. Then, starting around 4 years ago, we started to have module glass failures with our SunPower commercial systems and these Unirac clamps. We immediately switched to torque wrenches for tightening the clamps. However, the failures continued. My guess is that the poor design of the Unirac mid clamps in conjunction with thinner \u201cweaker\u201d module frames exasperated the issue. We now have stopped using those mid clamps and continue to hand tighten all clamps. We primarily install SunPower, and their residential module frames have a lip so all the pressure from the clamp doesn\u2019t go to the glass. </div><div dir="auto"><br></div><div dir="auto">Getting to your question - what kind of mid clamps do you have? If they are aluminum, there may be less risk than the stainless clamps. I would be worried that the process of loosening and then re-tightening might cause more damage than good if there aren\u2019t any problems that have occurred to date. It\u2019s a good question.</div><div dir="auto"><br></div><div dir="auto">August</div><div dir="auto">Luminalt</div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Sep 3, 2021 at 12:06 AM Corey Shalanski <<a href="mailto:coresolar@gmail.com">coresolar@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)"><div dir="ltr">Wrenches,<div><br></div><div>(This question actually does refer to the proper use of 'wrenches'...)</div><div><br></div><div>While inspecting some recent work from one of our contractors, we noted that the PV module clamps had been torqued to ~150% of the racking manufacturer's specified value. My question is whether that might have any detrimental effect on the modules (frame, glass, cells, seal, etc) and whether it would be worth loosening the clamps and re-torquing them to the proper spec? For reference, 224 modules are installed.</div><div><br></div><div>We were made aware that the contractor used an impact driver on the clamps, which accounts for the excessive torque applied. I definitely understand the temptation to use an impact driver for just about any hardware that needs turning\u2014but my understanding is also that impact drivers are generally incompatible with machine screws. So my other question to the group is whether anyone has had success in dissuading subcontractors from using impact drivers so liberally on project sites? Any advice is appreciated.</div><div><br></div><div>--</div><div>Corey Shalanski</div><div>Jah Light Solar</div><div>Portland, Jamaica</div></div>
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</blockquote></div></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">August Goers<br>Luminalt<br>o: 415.792.6666<br>m: 415.559.1525<br><a href="mailto:august@luminalt.com">august@luminalt.com</a></div>