<div dir="ltr"><div>It looks like Oncor is using the total generation facility nameplate of PV + ESS inverter ratings, or something along those lines. That's the same as we see in PG&E territory here in California. You might be able to use a PCS setting to limit grid battery charging and then maybe use Aggregate power export limit (see 5.4):</div><div><br></div><div><a href="https://enphase.com/download/power-control-system-integration-enphase-energy-system-tech-brief">https://enphase.com/download/power-control-system-integration-enphase-energy-system-tech-brief</a></div><div><br></div><div>There are many solutions that PCS will provide if the utility recognizes PCS as a bonafide solution.</div><div><br></div><div>-August</div><div><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div dir="ltr"><div dir="ltr"><p><br></p></div></div></div></div></div><br></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Wed, Nov 26, 2025 at 6:57 AM scot.arey--- 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="msg-3328862562595779709">
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In my 13 years installing solar in Texas, I've never had a utility come back and say "you must set a PCS limit of 2KW through this 25KW transformer or you can pay to upgrade the transformer."<br>
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System is 12KW of solar (9KW AC equiv.) and 6x Enphase 5P batteries (23KW AC) so total of 32KW of potential power export if the batteries were grid-exporting at same time of peak solar production. I can see the batteries charging at 23KW if charging from grid
but of course solar can never be a load. And exporting battery power simply not a financially smart option.</div>
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So the only answer I can come up with is this transformer is serving more than this home and seems undersized by utility if it's serving multiple homes with 200-amp services. Few words from Oncor is that this is the issue.<br>
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I alerted Oncor to the Power Control System capabilities to limit power export and they are insistent that 2KW is all they can take (they never said if this a import or export limit). I asked if this was a grid-tied system only with no ESS, would it have come
back with the same 9KW (AC) limit? I think they are tripping over the combined connected capacity of solar + ESS.<br>
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Anybody else in Texas running into this recently? I told Oncor I'd be perfectly fine with 9KW export capability (the solar) and limit grid-charging to this power, too.<br>
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This isn't Hawaii...so I'm super surprised and about to lose a lot of money.</div>
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<b>Howard "Scot" Arey</b></div>
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