<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr"></div><div dir="ltr">Hi William,</div><div dir="ltr"><br></div><div dir="ltr">One possible path forward would be to ask the utility co what AC inverter capacity would be allowed. Maybe the solution would be to unplug a micro or two if you are just over the limit. Even better, maybe they would allow you set an export limit on the micros you have installed.</div><div dir="ltr"><br></div><div dir="ltr">I had a recent situation where a 40kW DC system had exceeded a utility transformer by only 2kW AC, so a simple redesign avoided an $8k invoice from the utility. The utility was not transparent about this option at first and only made it clear after some persistence.</div><div dir="ltr"><br></div><div dir="ltr">Good luck,</div><div dir="ltr"><br></div><div dir="ltr">Garrison Riegel</div><div dir="ltr">Celestar Solar</div><div dir="ltr"><br><blockquote type="cite">On Dec 25, 2022, at 3:14 PM, Darryl Thayer via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">\ufeff<div dir="ltr"><div class="gmail_default" style="font-family:times new roman,serif;font-size:large">It is common practice for the utility to overload the transformer a lot for the potential load. They expect no one will use their service at maximum, furthermore, they expect non coincidence of loads. Look at the transformer most have a label as to the kW or the unit, and the utility should give you that number along with the impedance. Note I have had area engineers not understand that solar reduces the load on the transformer. They have two concerns, you will overload and you will raise the voltage to other customers. Overload is ridiculous; the transformer must be at least 20 kW if a 15 kW concern is valid. However, raising the voltage is not. If all the customers shut off their power, the voltage would rise to the inverter limit,and/or feed current back on the distribution line raising up/downstream customers voltage. I have had this problem, on three occasions discussions with the utility upper engineering, not local engineer, i prevailed, one case I did not. In one cast utility allowed connection and put a voltage monitor on secondary voltage, then later allowed permanent connection.. Good luck </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Dec 25, 2022 at 1:16 PM William Miller via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</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 class="msg7831789815957074960"><div lang="EN-US"><div class="m_7831789815957074960WordSection1"><p class="MsoNormal"><span style="font-size:12pt;font-family:Verdana,"sans-serif"">Wrenched:</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"">Merry Christmas to those of you that observe such traditions, or substitute the winter festivity of your choice.</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 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="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"">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="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 would appreciate any insight on how to consider this situation and how to fight it.</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"">Sincerely,</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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