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<p><span style="font-size: 12pt;">William, </span></p>
<p><span style="font-size: 12pt;">I ran into this once on an old transformer, which fortunately they changed at no cost. It was a 10 kW transformer on a 200 A (48 kW) service. They had some dimming of lights on heavy loads, and the transformer was changed out on that basis, at no charge. </span></p>
<p><span style="font-size: 12pt;">My questions for the utility would be?</span><span style="font-size: 12pt;"></span></p>
<ul>
<li><span style="font-size: 12pt;">Are there any other PV systems feeding the transformer?</span>
<ul>
<li><span style="font-size: 12pt;">If so, what is their maximum production.</span></li>
</ul>
</li>
<li><span style="font-size: 12pt;">What size is the transformer?</span></li>
<li><span style="font-size: 12pt;">What percentage of transformer capacity is allowed to be back-fed.</span></li>
</ul>
<p><span style="font-size: 12pt;">If the math comes out in your favor, you will have a good case to escalate to the next level. </span></p>
<p><br /></p>
<p><span style="font-size: 12pt;">Good Luck,</span></p>
<p><span style="font-size: 12pt;">Drake</span></p>
<p><br /></p>
<p>Drake Chamberlin</p>
<p>Athens Electric LLC</p>
<p>Ohio Electrical Contractor’s License 44810</p>
<p>CO Master Electrician’s License 4526</p>
<p>NABCEP Certified PV Installation Professional</p>
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<p id="reply-intro">On 2022-12-25 13:58, William Miller via RE-wrenches wrote:</p>
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<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';">Wrenched:</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';"> </span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';">Merry Christmas to those of you that observe such traditions, or substitute the winter festivity of your choice.</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';"> </span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';">I helped a previous employee install an Enphase IQ8 system on his home. He applied for the utility approval concurrently with his building permit The day he got his final inspection the utility contacted him and claimed "The aggregate generation exceeds the identified transformer rating" and refused him a Permission to Operate letter.</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';"> </span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';">Adding up the service ratings of the homes on his secondary we get about 336 kW of potential consumption. Adding the grid-tied systems on his secondary we get about 16.5 kW. How is it that the back-feed exceeds the transformer rating?</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';"> </span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';">I would appreciate any insight on how to consider this situation and how to fight it.</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';"> </span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';">Sincerely,</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';"> </span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';">William Miller</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Verdana','sans-serif';"> </span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Arial','sans-serif';">Miller Solar</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Arial','sans-serif';">17395 Oak Road, Atascadero, CA 93422</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Arial','sans-serif';">805-438-5600</span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Arial','sans-serif';"><a href="http://www.millersolar.com/" target="_blank" rel="noopener noreferrer">www.millersolar.com</a></span></p>
<p class="v1MsoNormal"><span style="font-size: 12.0pt; font-family: 'Arial','sans-serif';">CA Lic. 773985</span></p>
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