<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><div dir="ltr"><div>William,</div><div><br></div><div> I agree that AC coupled input power can't be "directly" regulated by the battery inverter, but it *can* be indirectly regulated using techniques such as telling the downstream PV inverter(s) to back off via a frequency-watt change, or turning on a diversion load, or worst case simply shutting off the battery inverter AC output connected to the PV inverters (so-called bang-bang control). However, I thought the battery charging parameters were part of the equation when the inverter is making the decision about what to do if the batteries are nearly full?</div><div><br></div><div> And in my case, with the SI master set to EXT-BMS (most recent firmware), the battery parameters *could* be set and appeared to make a difference in operation. My (possibly incorrect!), assumption was that the closed loop communication was primarily for SOC and fault conditions. If there is any documentation for what the closed loop communication consists of that would be really interesting!</div><div><br></div><div>Cheers,</div><div><br></div><div>Kirk Bailey</div><div><a href="mailto:kirk@abundantsolar.com">kirk@abundantsolar.com</a></div><div>541-231-8072 x1</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Nov 12, 2023 at 4:38\u202fPM 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 class="msg-7508858173050669440"><div lang="EN-US"><div class="m_-7508858173050669440WordSection1"><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">Kirk:</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">There are a lot of misconceptions about AC Coupling in the industry. I think you may have fallen victim to one:</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">When you are feeding AC power backwards through a battery inverter, that inverter cannot exert any control over the charging parameters. You can set bulk, absorption, float, EQ, any charge setting you can find, but if your power source is AC-coupled (coming in through the out door), those settings do not affect the charging at all.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">Someone please slap me if I am wrong on this.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">Those settings do apply if you have an AC source like a generator or grid that is connected to an AC <u>input</u>. We cannot connect grid-tied inverters to any input because AC inputs do not create a mini-grid.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">Furthermore, if you set a Sunny Island for battery type \u201cExt BMS\u201d, you cannot adjust those settings. Pressing the buttons elicits wonky responses. Pressing up arrow jumps to zeros\u2026 Pressing the down arrow can reduce settings but they will not be saved. I have seen this and while Fortress cannot replicate this in the lab, they have heard this reported. (This Ext-BMS setting is only available with the latest firmware and by initiating New battery or New system in the quick programming function.)</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">Until this moment I did not realize that this is another reason Closed loop on a </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">Sunny Island is a non-starter: If you can\u2019t set charge parameters for generator or grid battery charging then you have a system that cannot be set to charge batteries from AC sources with precision. If closed loop does not work for this reason, and open loop does not track the critical SOC values, then we may be out of options. Maybe this is why SMA will not talk to anyone with lithium batteries.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">Hmmmmm\u2026</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)">William</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:rgb(31,73,125)">Miller Solar</span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:rgb(31,73,125)">17395 Oak Road, Atascadero, CA 93422</span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:rgb(31,73,125)">805-438-5600</span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:rgb(31,73,125)"><a href="http://www.millersolar.com/" target="_blank"><span style="color:blue">www.millersolar.com</span></a></span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:rgb(31,73,125)">CA Lic. 773985</span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";color:rgb(31,73,125)"> </span></p><p class="MsoNormal"><b><span style="font-size:10pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10pt;font-family:"Tahoma","sans-serif""> Kirk Bailey [mailto:<a href="mailto:kirk@abundantsolar.com" target="_blank">kirk@abundantsolar.com</a>] <br><b>Sent:</b> Sunday, November 12, 2023 3:05 PM<br><b>To:</b> <a href="mailto:william@millersolar.com" target="_blank">william@millersolar.com</a>; RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Integrating Fortress E-vault maxes into an SI AC-coupled system</span></p><p class="MsoNormal"> </p><div><div><p class="MsoNormal">I went back and looked at my notes on my recent adventure with closed loop SI to eFlex Fortress, and one thing I had noted at the time is that Fortress recommends 2.2V, 2.26V, and 2.3V for the setting for ChrgVtgFlo (220-10), depending on which of three Fortress docs I read. I think I ended up setting it to 2.26V after some experimentation.</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">I can imagine a scenario where the voltage gets *slightly* too high, activating the most trigger-happy of the battery's BMS's, and the resulting sudden partial loss in load then causes a transitory voltage surge from the SI, which then...</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Cheers,</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Kirk Bailey</p></div><div><p class="MsoNormal"><a href="mailto:kirk@abundantsolar.com" target="_blank">kirk@abundantsolar.com</a></p></div><div><p class="MsoNormal"> </p></div></div><p class="MsoNormal"> </p><div><div><p class="MsoNormal">On Sun, Nov 12, 2023 at 2:36\u202fPM William Miller via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>> wrote:</p></div><blockquote style="border-color:currentcolor currentcolor currentcolor rgb(204,204,204);border-style:none none none solid;border-width:medium medium medium 1pt;padding:0in 0in 0in 6pt;margin-left:4.8pt;margin-right:0in"><div><p class="MsoNormal">Jay:</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Good question. I assumed some kind of FET circuit but that is only my assumption. </p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">However an open relay exhibits some fairly high impedance. </p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">The symptoms indicate the SI shuts down but the batteries remain connected. Something allows 69 volts on the battery terminals\u2026<br clear="all"></p><div><div><p class="MsoNormal"><br>William Miller<br>Miller Solar.com<br>805-438-5600<br><a href="http://www.millersolar.com" target="_blank">www.millersolar.com</a></p></div></div></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal"> </p><div><div><p class="MsoNormal">On Sun, Nov 12, 2023 at 2:22 PM Jay via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>> wrote:</p></div><blockquote style="border-color:currentcolor currentcolor currentcolor rgb(204,204,204);border-style:none none none solid;border-width:medium medium medium 1pt;padding:0in 0in 0in 6pt;margin-left:4.8pt;margin-right:0in"><div><div><p class="MsoNormal">Maybe someone else knows differently but it was explained to me that the fortress batteries have a relay that disconnects the battery if the voltage gets to high or low. There isn\u2019t any electronic device to change battery impedance besides what the actual cells are doing. </p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Jay</p></div><div><p class="MsoNormal"><br><br></p><p class="MsoNormal" style="margin-bottom:12pt">On Nov 12, 2023, at 12:50\u202fPM, Jerry Shafer via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>> wrote:</p></div><blockquote style="margin-top:5pt;margin-bottom:5pt"><div><p class="MsoNormal"><span style="font-family:"Tahoma","sans-serif"">\ufeff</span></p><div><p class="MsoNormal">Regarding the SI Inverters,for me it works best to eliminate the bat temp sensor and put in a resister set to be 75 degrees, this will prevent the charger over under charge issue.</p><div><p class="MsoNormal">Fun times </p></div></div><p class="MsoNormal"> </p><div><div><p class="MsoNormal">On Sun, Nov 12, 2023, 12:36 PM William Miller via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>> wrote:</p></div><blockquote style="border-color:currentcolor currentcolor currentcolor rgb(204,204,204);border-style:none none none solid;border-width:medium medium medium 1pt;padding:0in 0in 0in 6pt;margin-left:4.8pt;margin-right:0in"><div><div><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">Friends:</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">I am still working on getting the E-vaults to play nice with the Sunny Islands and Sunny Boys.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">With Open loop I was getting significant discrepancies in the reporting of SOC in the e-vaults versus that reported by the SI inverters. This discrepancy did not diminish over time. The discrepancy caused unacceptable charging and generator operations.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">I got Closed loop hooked up, but I found that every few days the SI inverters would shut down due to a battery over-voltage condition. I believe that when the e-vaults are near 100% SOC the BMS units increase the battery impedance which means any charging current applied will cause the voltage spike I have been seeing. I was able to measure these conditions myself on site, although they were very fleeting and required recording with the Fluke87 Min-Max function (love this meter!).</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">I was able to extract log files from the Sunny Island primary inverter and perform some analysis. It appears when I turned on remote BMS on the SI (as part of the Closed loop protocol) it disabled the Frequency-Shift Power Control. This means the SI inverters have gone from having poor control over battery charging to having no control over battery charging.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">I have documented my research <a href="https://millersolar.com/MillerSolar/case_studies/36_SIFortress/36_SunnyIslandFortressIntegration.html#Inhibit" target="_blank">here</a>. There is a table of contents to take you to the latest information. I appreciate pertinent comments any of you might have.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">By the way, if anyone has called SMA tech support for help on a Sunny Island system, you have likely been asked to extract log files, zip them up and send them off for review (and waited a long time for a reply). I am the kind of guy who does not like to wait for solutions and who likes to figure out things for himself. I have taught myself how to evaluate those log files. I will be posting a web page on the subject. In the meantime, if you are interested, two of my analysis Excel sheets are linked in the case study. I will be expanding on this and providing resources to any integrator that wants that knowledge.</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">Thanks in advance for any insight. I hope I am wrong about this and I am just missing something. I also hope revealing my headaches will help someone someday\u2026</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif"">William</span></p><p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">Miller Solar</span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">17395 Oak Road, Atascadero, CA 93422</span></p><p class="MsoNormal"><span style="font-family:"Arial","sans-serif"">805-438-5600</span></p><p class="MsoNormal"><span style="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-family:"Arial","sans-serif"">CA Lic. 773985</span></p><p class="MsoNormal"> </p><p class="MsoNormal"> </p></div></div><p class="MsoNormal" style="margin-bottom:12pt">_______________________________________________<br>List sponsored by Redwood Alliance<br><br>Pay optional member dues here: <a href="http://re-wrenches.org" target="_blank">http://re-wrenches.org</a><br><br>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org" target="_blank">RE-wrenches@lists.re-wrenches.org</a><br><br>Change listserver email address & settings:<br><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br><br>There are two list archives for searching. 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