<div dir="ltr">Hi Scot, <div><br></div><div>In my experience backing up a 400A service with two Sol-Ark 15K inverters, it's critical to use a single battery bank and to parallel both the inverter inputs and outputs. I initially attempted to configure two interdependent Sol-Arks to work together, but encountered monitoring communication issues and was informed by Sol-Ark tech support that data would be skewed if the inverteres were on the same utility transformer and were not run in parallel. Hope this helps.</div><div><br></div><div>Best,</div><div><br></div><div>Chris</div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Fri, Jun 27, 2025 at 3:05 PM 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="msg5555391242016751333">
<div dir="ltr">
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Seeking your feedback and best practices.</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
We have a existing customer who wants to add ESS for whole house backup. He has a 400-amp meter box with two 200-amp panels on each side of the meter can. We want to use Sol-Ark and HomeGrid which is our go-to solution. Today, we have two 10KW ground mounts
feeding a grid-tied system with Fronius inverters aggregated at the array with single set of conductors back to the house and meter</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Option 1: Add a SolArk 15KW and HomeGrid '4-stack' per each 200-amp panel and in essence have two separate systems each backing up their own panelboard. Seems easy but I know the panels are not totally balanced and this seems like I'm having excess capacity
at the panel that powers circuits to run less than all the time.</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Brings me to option 2:</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Install two <span style="font-size:16px">paralleled </span>SolArks with two batteries again (and now a battery combiner) and add a 400-amp transfer switch and take grid output from meter and bring to ATS first. The GEN inputs on ATS will be fed by aggregated
LOAD outputs of the SolArks so if grid fails, the ATS "sees" 240V and transfers to the inverters only and opens circuit to grid. When grid power is there, all is grid-tied and bi-directional. I've done similar setup with Outback Radian and ASCO 200A ATS for
whole house backup.</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
But this seems really complicated with lots of extra boxes. </div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Take the simple-easy route even if one inverter is a bit too much for one of the 200-amp panels? Ot aggregate and use ATS so we can put two SolArks to work together to address full load as one operating output? Wall space for this is pretty good for both options.</div>
<div id="m_5555391242016751333Signature">
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="direction:ltr;text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(36,36,36)">
<b>Howard "Scot" Arey</b></div>
<div style="direction:ltr;text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(36,36,36)">
<b>Owner, Solar CenTex</b></div>
<div style="direction:ltr;text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(36,36,36)">
<br>
</div>
<div style="direction:ltr;text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(36,36,36)">
NABCEP PV Installation Professional</div>
<div style="direction:ltr;text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(36,36,36)">
TECL 29755</div>
<div style="direction:ltr;text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(36,36,36)">
254-300-1228 </div>
<div style="text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<img id="m_5555391242016751333x_image_0" width="105" height="105" style="width: 105px; height: 105px; max-width: 722px; min-width: auto; min-height: auto; margin: 0px;" src="cid:ii_197bc29b5f96893c0bb1"></div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
</div>
</div>
_______________________________________________<br>
List sponsored by Redwood Alliance<br>
<br>
Pay optional member dues here: <a href="http://re-wrenches.org" rel="noreferrer" 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" rel="noreferrer" target="_blank">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br>
<br>
There are two list archives for searching. When one doesn't work, try the other:<br>
<a href="https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/" rel="noreferrer" target="_blank">https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/</a><br>
<a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" rel="noreferrer" target="_blank">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br>
<br>
List rules & etiquette:<br>
<a href="http://www.re-wrenches.org/etiquette.htm" rel="noreferrer" target="_blank">http://www.re-wrenches.org/etiquette.htm</a><br>
<br>
Check out or update participant bios:<br>
<a href="http://www.members.re-wrenches.org" rel="noreferrer" target="_blank">http://www.members.re-wrenches.org</a><br>
<br>
</div></blockquote></div>