<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>I disagree about tarps. We've tested fully covered arrays (and small ones at that) and still had what would be considered lethal levels of current and voltage, even when using heavy, reflective tarps. And it can be very difficult to ensure they stay in place, plus it's impractical for larger arrays. <br><br>Brian</div><div><br>On Sep 24, 2015, at 6:31 AM, Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com">jason@floridasolardesigngroup.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif">"In this scenario, there is no safe way to replace either of the two Morningstar controllers."</div><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif"><br></div><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif">The BEST rooftop disconnect remains... a big thick tarp. Not totally practical in an emergency situation, but it is pretty fail safe. </div><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif"><br></div><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif">Unfortunately for emergency responders, that does not take care of the AC circuits in a microinverter or AC module system, but ideally the building main is shut down anyway, and the risk is the same as any other 240V equipment/appliance circuits.</div><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif"><br></div><div class="gmail_extra"><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><span><div dir="ltr" style="margin-left:0pt"><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif;display:inline">Jason Szumlanski</div></div><div dir="ltr" style="margin-left:0pt"><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif;display:inline"><br></div></div><div dir="ltr" style="margin-left:0pt"><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif;display:inline"><br></div></div></span></div></div></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Wed, Sep 23, 2015 at 4:26 PM, William Miller <span dir="ltr"><<a href="mailto:william@millersolar.com" target="_blank">william@millersolar.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">Dear Fellow Wrenches</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">Below is a design conundrum that may resonate with some of you:</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">We are finalizing a design for an off-grid residential system. The customer insist the PV should be on the roof and pre-installed a 1-1/4” PVC conduit from his roof to a crawl space, in anticipation of a solar install. This created real problems, because we all know we can’t pull PV source or output circuits in (or now, on) the envelopes of habitable buildings.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">There was no practical way to replace the PVC. We contrived a method to sleeve ¾” liquid-tight through the 1-1/4” PVC to the crawl space, continuing on with EMT. This is the largest metallic conduit we could fit. The distance was greater than 10 feet so we couldn’t use EMT. Due to the conduit size restriction, we upgraded to Morningstar 600 volt charge controllers, allowing us to reduce conductor size.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">(As a sidebar, although the Morningstar is listed as a 600 volt charge controller, we have found no circumstance were we could take advantage of that high a voltage. With the currently available high wattage modules, by the time we added enough in series to get to 600 volts, we were well beyond the wattage capabilities of the controller. For sake of design considerations, I suggest one regard these units as ~300 volt charge controllers.)</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">We now have plans for 300 volt PV feeders running down an interior wall and under the house, with no roof-top disconnecting means. It is my understanding none are required. I am not comfortable with this. </span></p><div class="gmail_default" style="font-family:'trebuchet ms',sans-serif;display:inline"></div>In this scenario, there is no safe way to replace either of the two Morningstar controllers. Should someone drill through or damage the EMT in the wall or under the floor, there would be no way to turn off the feeder.<p></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">I don’t like putting HU361RBs on a roof. They must remain vertical and so they stick up too high and are hard to provide mounting for. Sola-deck units are another option, but they require integrating with shingles, not practical on this job or many others. I finally settled on a DC-Sunvolt PV-X16A-4X-RG disconnect as a possible solution. At $216 it is not out of range. The unit will provide means to turn off the feeders for service. I will report back on my impressions of the unit.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">To distill this scenario, I don’t believe the code requires a disconnect, but I feel morally obligated to install one. I’d be interested in verification of the code interpretation and others response to similar situations.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">I found no other options for rooftop disconnecting means that would be small, reasonably priced and not present a high profile. If there are products I don’t know about, I would be most grateful to receive your input.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">While researching the hardware I stumbled upon this article, linked below. It seems to present a real dilemma, but I am not convinced. Please remain skeptical as you read. It appears all of the links direct you to the same source.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"><a href="https://www.linkedin.com/pulse/greatest-debacle-solar-pv-australias-rooftop-dc-isolator-lucas-sadler" target="_blank">https://www.linkedin.com/pulse/greatest-debacle-solar-pv-australias-rooftop-dc-isolator-lucas-sadler</a></span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">Thanks again to all of you for helpful advice and expertise. I learned about Sunvolt here, just one of many great suggestions.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">Sincerely,</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">William Miller</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif;color:black"><img border="0" width="64" height="28" src="cid:image002.jpg@01D0F25F.0AB20C40" alt="Gradient Cap_mini"></span><span style="font-size:10pt;font-family:Arial,sans-serif;color:black"><br>Lic 773985<br><a href="http://www.millersolar.com/" target="_blank">millersolar.com</a><br><a href="tel:805-438-5600" value="+18054385600" target="_blank">805-438-5600</a></span></p><p class="MsoNormal"> </p></div></div></blockquote></div></div></div>
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