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</head><body text="#000000"><span style="font-size: 18px;">Hi Folks,</span><span
style="font-size: 18px;"><br>
</span><span style="font-size: 18px;"><br>
</span><span style="font-size: 18px;">Just wanted to make a correction
on the EG4</span><span><span style="font-size: 18px;"> 18kPV of a
statement made during the AC Coupling thread.<br>
</span></span><span><span style="font-size: 18px;"><span><span
style="font-size: 18px;"><br>
</span><span style="font-size: 18px;">The EG4 18kPV does have
frequency shift based AC Coupling. The confusion comes from the fact
that like Sol-Ark there is a SOC set-point override feature for AC
Coupling but the video William referred to seemed to imply it is the
only control. It is not and EG4 is fixing this video.</span></span></span></span><br>
<span><span style="font-size: 18px;"><span><span style="font-size:
18px;"><span><span style="font-size: 18px;"><br>
</span><span style="font-size: 18px;">William Miller wrote</span><span
style="font-size: 14px;">:<br>
</span></span><br>
<span><span style="font-size: 14px;"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">EG4:
I read the manual and it looks like the EG4 works just like
the Sol-arc: You program the generator input to actually be an output.
The EG4 abruptly disconnects that output when battery SOC reaches a
programmed level-- There is apparently no frequency shift function.<br>
</span></span></span><br>
Hope that helps,<br>
<br>
Jeff<br>
Clearwater<br>
Village Power Design<br>
<a href="http://www.villagepowerdesign.com">www.villagepowerdesign.com</a><br>
</span></span></span></span><span><span style="font-size: 14px;"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"><br>
</span></span><span style="font-size: 14px;"></span><br>
</span>
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<a style="color:#485664
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style="display:inline-block;white-space:nowrap;vertical-align:middle;width:48%;text-align:
right;"> <font color="#909AA4"><span style="padding-left:6px">October
28, 2023 at 10:49 PM</span></font></div> </div></div>
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--></style><div class="WordSection1"><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">Jay:</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">I
am not sure how it would be possible for a grid-tied inverter to
operate with any battery inverter if it was not connected to the battery
inverter AC output. The grid-tied inverter needs to see correct
voltage and frequency before it can start up. How else could this work?</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">I
looked up all of the inverters you cited. In each case it may look to
you like you are connecting to an input, it is really just reprogramming
the inverter to turn the generator input into an extra output. All of
the manufacturers provide warnings about doing this. Here is more
information from each of the manufacturers:</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">Sol-arc:
From the manual for the Sol-arc 15K-2P-N: You convert the Gen input to
an output and make that your connection point. “<i>A full AC coupled
solar system is not recommended as power control and monitoring is
limited.”</i> </span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">EG4:
I could not find an “ev4” inverter anywhere online. There is an EG4
inverter. I read the manual and it looks like the EG4 works just like
the Sol-arc: You program the generator input to actually be an output.
The EG4 abruptly disconnects that output when battery SOC reaches a
programmed level-- There is apparently no frequency shift function. The
manual is pretty inadequate on this point but they do provide a <a
href="https://www.youtube.com/watch?v=vRAq9g34VcI&ab_channel=EG4Electronics"
moz-do-not-send="true">video</a>.</span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">Fortress:
The same as above is true about using the generator input for
AC-coupling on the Fortress FP-Envy-12k. From that manual<i>: It is
forbidden to connect the Generator in Gen Port when AC Coupled. </i>That
is because when AC-coupling, the generator input is no longer an input.</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">So
while it appears one connects an AC-Coupled inverter to battery
inverter inputs, it is just a reprogramming of the generator input to be
an output. In all cases that I can see there is still no voltage
control of AC-coupled battery charging.</span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">I
am aware that to try and provide some modicum of control over the
battery charging from AC-coupled sources, a scheme was invented to shift
the output frequency and taper or shut down AC-coupled power. This is a
work-around, not a design. In each and every one of these systems it
is pretty clear there is little control over battery charging voltage.
These systems do not support three stage battery charging like a DC
charge controller can.</span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">When
AC-coupled charging is connected to batteries with BMS in certain
conditions battery voltage spikes can occur. See section 2.2 of this <a
href="https://www.victronenergy.com/live/ac_coupling:start"
moz-do-not-send="true">article.</a></span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">There
are limited advantages to AC coupling:</span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1
lfo1"><span style="font-size:12.0pt;font-family:Symbol;color:#1f497d"><span
style="mso-list:Ignore">·<span style="font:7.0pt "Times New
Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">AC
coupling allows reduced wire gauge for long-haul feeders. This is no
longer as necessary with new 600 volt input charge controllers.</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1
lfo1"><span style="font-size:12.0pt;font-family:Symbol;color:#1f497d"><span
style="mso-list:Ignore">·<span style="font:7.0pt "Times New
Roman""> </span></span></span><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">AC
Coupling allows an easier upgrade path for a customer that has
grid-tied inverters and wants to add batteries. I am not sure most
batteries can survive for long with the crude charging algorithm
provided, so I would hesitate to recommend this.</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">In
my opinion AC-coupled battery charging with even the newest inverters
is a crude affair. I am not a fan.</span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d">William</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><div><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:#1f497d">Miller
Solar</span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:#1f497d">17395
Oak Road, Atascadero, CA 93422</span></p><p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:#1f497d">805-438-5600</span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:#1f497d"><a
href="http://www.millersolar.com/" moz-do-not-send="true"><span
style="color:blue">www.millersolar.com</span></a></span></p><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:#1f497d">CA
Lic. 773985</span></p><p class="MsoNormal"><span style="color:#1f497d"> </span></p></div><p
class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Verdana","sans-serif";color:#1f497d"> </span></p><div><div
style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in
0in"><p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
Jay [mailto:<a href="mailto:jay.peltz@gmail.com" moz-do-not-send="true">jay.peltz@gmail.com</a>]
<br><b>Sent:</b> Saturday, October 28, 2023 1:58 PM<br><b>To:</b> <a
href="mailto:william@millersolar.com" moz-do-not-send="true">william@millersolar.com</a>;
RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] AC Coupling</span></p></div></div><p
class="MsoNormal"> </p><div><p class="MsoNormal">I’m going to both
agree and disagree </p></div><div><p class="MsoNormal"> </p></div><div><p
class="MsoNormal">Agree The older inverters ( Schneider, Outback, etc)
your drawing is correct. </p></div><div><p class="MsoNormal"> </p></div><div><p
class="MsoNormal">Disagree For many new inverters ( sol ark, ev4,
fortress) they bring ac coupling into the inverter directly. </p></div><div><p
class="MsoNormal">Usually on the generator input and not in the backup
loads panel. </p></div><div><p class="MsoNormal"> </p></div><div><p
class="MsoNormal">And I will also disagree about the statement that
these inverters are not designed for ac coupling. </p></div><div><p
class="MsoNormal">Agreed that the earlier non rule 21 compliant versions
didn’t have any internal control and required external relay control to
prevent overcharge. </p></div><div><p class="MsoNormal"> </p></div><div><p
class="MsoNormal">Newer versions of Schneider, OB, have frequently
shift which works with newer gt inverters to address the ac coupling
overcharge concerns. While creating potential new issues for loads with
up to 64 hz. </p></div><div><p class="MsoNormal"> </p></div><div><p
class="MsoNormal"> </p></div><div><p class="MsoNormal">Jay</p></div><div><p
class="MsoNormal"> </p></div><div><p class="MsoNormal"> </p></div><div><p
class="MsoNormal"> </p></div><div><p class="MsoNormal"> </p></div><div><p
class="MsoNormal"><br><br></p><p class="MsoNormal"
style="margin-bottom:12.0pt">On Oct 28, 2023, at 2:15 PM, William Miller
via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org"
moz-do-not-send="true">re-wrenches@lists.re-wrenches.org</a>> wrote:</p></div></div>
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