<div dir="ltr">Hi William - You raise a great question - can you install 600 VDC modules on a 1000 VDC SolarEdge system? Of course the DC optimizer output circuit would need to be rewired with 1000 VDC wiring and connectors, but I think the answer is "yes." According to <a href="https://www.solaredge.com/sites/default/files/application_notes_string_combiners_na.pdf">this article</a>, "In a SolarEdge system, the PV modules are isolated from the DC output circuit by the power optimizer." To me, it sounds like there is no risk of going over the max optimizer input voltage. I would want to verify this with SolarEdge prior to designing any systems, but it seems like a good idea to explore!<div><br></div><div>I was recently on another group chat, and someone mentioned being in a similar predicament to you. They want to upgrade an old central inverter. Anyway, they had found that the SMA CORE1 33 kW unit at least can be strung up to work with 600 VDC modules and wiring: <a href="https://files.sma.de/downloads/STPCORE1-DS-en-28.pdf?_ga=2.30799225.717469396.1631144387-1894865662.1631144383">https://files.sma.de/downloads/STPCORE1-DS-en-28.pdf?_ga=2.30799225.717469396.1631144387-1894865662.1631144383</a></div><div>I'm sure you'd have to redo a lot of the conduit and wire to accommodate several smaller inverters, but this might be worth exploring as well.</div><div><br></div><div>August</div><div><div>Luminalt</div><div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Sep 8, 2021 at 4:13 PM William Miller <<a href="mailto:william@millersolar.com">william@millersolar.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div lang="EN-US"><div class="gmail-m_-5199744743169752237WordSection1"><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif">Friends:</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;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:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif">I am working on a <a href="https://millersolar.com/MillerSolar/Portfolio/Commercial/CommercialTracker/CommercialTracker.html" target="_blank">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:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;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:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;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:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif">Here are the options I see:</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;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:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;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/" target="_blank">Here</a> is a paper on the subject.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;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:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif">Here is a <a href="https://millersolar.com/MillerSolar/case_studies/30-Re-Powering/re-powering.html" target="_blank">link</a> to a web-page I built for this project.</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif">Thanks,</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif">William Miller</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,sans-serif"> </span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">Miller Solar</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">17395 Oak Road, Atascadero, CA 93422</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">805-438-5600</span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif"><a href="http://www.millersolar.com/" target="_blank">www.millersolar.com</a></span></p><p class="MsoNormal"><span style="font-size:12pt;font-family:Arial,sans-serif">CA Lic. 773985</span></p><p class="MsoNormal"> </p><p class="MsoNormal"> </p></div></div>
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