<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">If you're in Sebastopol you could ask Paul Hernday at Solmetric if the PVA would help.<br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div><div><div><div><div><br class="Apple-interchange-newline">Blessings,</div><div><div>Kelly</div><div><br></div></div></div></div></div></div></div></div></span></span></div></span></div></span></div></span></div></span></span>
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<br><div><div>On Nov 26, 2012, at 4:55 PM, Robert Nuese wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Wrenches<div><br></div><div>I've been experiencing a troubleshooting problem that you may be able to</div><div>help me with. Or, can anyone refer me to someone, maybe an electrical</div><div>engineer?, who I could hire to help.</div><div><br></div><div>About 7 years ago I installed Unisolar modules on all the roofs of a complex</div><div>of 12 mixed use buildings and one commercial building. These fed the</div><div>grid through a variety of Fronius IG and SMA SunnyBoy inverters.</div><div><br></div><div>Ever since, we have had occasional intermittent ground faults on a few of</div><div>the roofs, and more frequent ones on one roof. At least some of these I</div><div>suspect were caused by the roofer. Standard procedure on the Unisolar</div><div>modules is to put two screws through them that hold on the roof ridge</div><div>z-strip metal closure piece. These also keep the modules from sliding off</div><div>the roof in extreme hot weather. I found a number of screws placed</div><div>slightly outside the allowed screw zone. After I'd moved the screws</div><div>(and removed the raised metal edges the screws had made in the roof,</div><div>and put insulation between roof and module in those locations), this has</div><div>seemed to fix some problems. Similarly, putting tefzel patches, per Uni-</div><div>solar instructions, on some big dings and scratches may have fixed some</div><div>others.</div><div><br></div><div>However, I still occasionally, rather rarely, get ground fault indications</div><div>on some inverters, and rather regularly get them on one specific IG 3000.</div><div>Some times the indication is just in the software, and the problem disappears</div><div>through resetting by disconnecting the inverter and reconnecting to reset the</div><div>software. However, on that worst Fronius, it has usually blown the 1 amp</div><div>ground fault fuse, indicating that there very likely has been a ground fault.</div><div><br></div><div>I suspect that these ground faults are brought on by thermal expansion and</div><div>contraction, that may only occasionally, and briefly, bring hot and ground</div><div>elements of the system into close enough proximity. Dampness seems to</div><div>play a part, the ground faults almost always occur during the rainy season,</div><div>and usually during a rainy period.</div><div><br></div><div>But whenever I get out to the site to test the system, the ground fault is</div><div>always gone. I test by disconnecting both wires of each string, measuring</div><div>the total voltage across, and then the voltage from each to ground. If there</div><div>is a clear voltage to ground, then there is a ground fault, and its location in</div><div>the string can be easily determined. If the voltage steadily goes toward</div><div>zero, then a ground fault is not clearly present, and the location of where</div><div>one had been is totally obscure.</div><div><br></div><div>I've done very thorough visual inspection of the roofs, and also of the</div><div>disconnects, junction boxes, and gutters that the wires pass through.</div><div>As mentioned, the modules have had some problems, and I've fixed them</div><div>all, as well as can be done. The wires all seem fine. Well connected, neat,</div><div>not close to raw metal edges, insulation ok, etc.</div><div><br></div><div>I've asked Unisolar (before they went bankrupt, now they don't answer the</div><div>phones), and they've just recommended the testing I've done, and not had</div><div>any other ideas. Same with Fronius - they think it's outside of the inverter,</div><div>and the blown fuses support that position.</div><div><br></div><div>I could go on with more details about what I've done and thought about,</div><div>for instance, is the Fronius too sensitive? But I'll catch my breath and see</div><div>if anyone else has some input before I go into more detail.</div><div><br></div><div>SO what am I missing? What test should I do? How can I fix this problem?</div><div><br></div><div>OR does anyone know of somebody with more expertise who I could hire</div><div>to help? I'm a fairly experienced solar installer, but I think this might be</div><div>something that requires an electrical (or electronic?) engineer with a deep</div><div>understanding of electrical theory, and with some advanced test equipment.</div><div>Any recommendations? Probably needs to be someone within 100 miles of</div><div>Sebastopol CA.</div><div><br></div><div>Thanks,</div><div>Robert Nuese</div><div><div><span class="Apple-style-span" style="border-collapse: separate; font-style: normal; font-variant: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; font-variant: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; font-variant: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><div style="font-family: 'Times New Roman'; font-size: medium; font-weight: normal; "><font class="Apple-style-span" face="Times New Roman"><br class="khtml-block-placeholder"></font></div><div style="font-style: normal; "><span class="Apple-style-span" style="font-size: 15px;"><b><br></b></span></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline">
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