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Youll need to either measure or calculate impedance from the inverters up to and ideally including the utility transformer. The most likely culprit are one or both are undersized.</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> RE-wrenches <re-wrenches-bounces@lists.re-wrenches.org> on behalf of James Reismiller <james@abundantsolar.com><br>
<b>Sent:</b> Thursday, May 20, 2021 10:52:06 AM<br>
<b>To:</b> re-wrenches@lists.re-wrenches.org <re-wrenches@lists.re-wrenches.org><br>
<b>Subject:</b> [RE-wrenches] Grid overvoltage and undervoltage issues on SMA install</font>
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<p class="x_MsoNormal">Hi Folks, </p>
<p class="x_MsoNormal">Im wondering if anybody has ideas on what could be causing grid over/undervoltage errors on an install we did about a year ago that now has these issues. The site is a 24 kW DC ground mount array with (3) SMA SB7.0-1SP-US-40 inverters.
Ive checked and done the following: </p>
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<li class="x_MsoListParagraph" style="margin-left:0in">Measured voltage min/max at inverter terminals and AC combiner. Min 228VAC (with no inverter output) Max - 269 VAC (when inverter trying to connect)!
</li><li class="x_MsoListParagraph" style="margin-left:0in">Had utility check service and transformer with load meter (with no PV running). No issues found and utility engineer stated he thinks its on our side.
</li><li class="x_MsoListParagraph" style="margin-left:0in">Checked all AC connections including neutral (seemed like neutral issue) from inverters back to supply-side tap (fused disco).
</li><li class="x_MsoListParagraph" style="margin-left:0in">Changed SMA upper voltage window in grid guard settings to 272V max and 264V reconnection. This helped for a while but now is faulting again.
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<p class="x_MsoNormal">Have any of you ran into this issue and how did you solve it? Or whats the next thing to check?
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<p class="x_MsoNormal">Thanks in advance! </p>
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<p class="x_MsoNormal">Be Well, </p>
<p class="x_MsoNormal">James Reismiller </p>
<p class="x_MsoNormal">He/Him/His </p>
<p class="x_MsoNormal"><span style="color:black">NABCEP Certified Solar PV Installer
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<p class="x_MsoNormal">Abundant Solar </p>
<p class="x_MsoNormal">541-231-8072 xt. 3 </p>
<p class="x_MsoNormal">CCB#175919 </p>
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