<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr">Hi william</div><div dir="ltr"><br></div><div dir="ltr">Here is possibly another option </div><div dir="ltr"><br></div><div dir="ltr">The sma 50 and 62 kw tripower core 1 have operating Mppt voltages down around 125-150vdc. </div><div dir="ltr"><br></div><div dir="ltr">I don\u2019t know how the system is wired: combiners and sub combiners? </div><div dir="ltr"><br></div><div dir="ltr">What about installing the inverters in place of the combiners, then AC runs</div><div dir="ltr">to the main AC buss via hanging wire trays. This eliminates the combiners, uses newer technologies, is probably a cheaper option buying time</div><div dir="ltr">Until a full repower with new modules/ inverters can happen. Those 50 kw units are $4500 each. </div><div dir="ltr"><br></div><div dir="ltr">Which is of course the other option in my mind, full rebuild. The repair + parts kit puts you close to $200k in the hole with ancient inverters and 10+ year old panels. I don\u2019t know if they can push more KW, but that array could probably be upgraded to double what it is now. With 125 kw string inverters, no combiners could be an option. </div><div dir="ltr"><br></div><div dir="ltr">There are going to be a lot of these issues in the future </div><div dir="ltr"><br></div><div dir="ltr">Let us know what option you figure out. </div><div dir="ltr"><br></div><div dir="ltr">Jay</div><div dir="ltr"><br></div><div dir="ltr"><br></div><div dir="ltr"><br><blockquote type="cite">On Sep 8, 2021, at 5:14 PM, William Miller <william@millersolar.com> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">\ufeff<meta http-equiv="Content-Type" content="text/html; charset=us-ascii"><meta name="Generator" content="Microsoft Word 14 (filtered medium)"><style><!--
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--></style><div class="WordSection1"><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Friends:</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">I learned a new buzzword recently: \u201cRe-powering.\u201d It means replacing inverters on an existing PV system of ten or more years old. Due to the high number of systems of this vintage it appears that re-powering has become somewhat of a sub-industry. The big problem is these systems are all 600 Volt limited PV panels, combiners and re-combiners and there are no 600 volt utility grade inverters being manufactured.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">I am working on a <a href="https://millersolar.com/MillerSolar/Portfolio/Commercial/CommercialTracker/CommercialTracker.html">utility scale system</a> built about 14 years ago that fits the description above. There are two 250KVA Xantrex GT250 inverters and one has failed. The question of the moment is: Repair or replace?</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Repair: If we fix these inverters, can we count on support in the future? We can negotiate a service contract with Schneider at a cost yet to be revealed. This requires we buy a spare parts kit for about $100K. There are a few other companies that claim to offer repair services on these inverters but none has followed through.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Replace: The PV plant is built with panels and BOS all limited to 600 VDC max. There are no more 600 volt input utility scale inverters being built, or at least none that I have found. If we install a 1000 or 1500 volt inverter we may have to replace the entire PV array and BOS. It may be possible to convert the output of the existing panels to a higher voltage with DC-DC converters. </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Here are the options I see:</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Optimizers: One purveyor of optimizers is Solar Edge. Solar Edge offers a 100 KVA inverter. This inverter requires DC input of 850 volts. The inverter requires optimizers to obtain this voltage. The question: Do the optimizers isolate the PV from the higher string voltages in the case of a catastrophic failure of one or more of the optimizers?</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Repower with outboard DC-DC voltage converters, such as provided by Alencon Systems. Solectria has successfully done this. <a href="https://alenconsystems.com/learning/pv-retrofits-with-transformerless-inverters/">Here</a> is a paper on the subject.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">If anyone has dealt with this issue before I would sure appreciate any wisdom.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Here is a <a href="https://millersolar.com/MillerSolar/case_studies/30-Re-Powering/re-powering.html">link</a> to a web-page I built for this project.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Thanks,</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">William Miller</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">Miller Solar</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">17395 Oak Road, Atascadero, CA 93422</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">805-438-5600</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif""><a href="http://www.millersolar.com/">www.millersolar.com</a></span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">CA Lic. 773985</span></p><p class="MsoNormal"> </p><p class="MsoNormal"> </p></div>
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