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Brian,<br>
<br>
Is this the drawing?<br>
Magnum <a
href="http://www.google.com/url?sa=t&source=web&cd=1&sqi=2&ved=0CBYQFjAA&url=http%3A%2F%2Fwww.magnumenergy.com%2FLiterature%2FApplication%2520Info%2FMagnum%2520AC%2520Coupled%2520Line%2520Diagram%2520%281-May-2010%29.pdf&rct=j&q=%22ac%20coupled%22%20site%3Awww.magnumenergy.com&ei=EZBiTte-H4jniAKNraDGCg&usg=AFQjCNG7FuyVaDx7YSWcJfqkh4TUkps4qA&cad=rja">ac
coupled diagram</a> from Google cache.<br>
<br>
Kent Osterberg<br>
Blue Mountain Solar<br>
<br>
<br>
<br>
Allan Sindelar wrote:
<blockquote cite="mid:4E61A962.1000908@positiveenergysolar.com"
type="cite">
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http-equiv="Content-Type">
Brian,<br>
Good job of laying it out. <br>
<br>
Now here's the part I'm missing. If as you say the grid-tied
inverter(s), either micro or string, are connected to the load side of
the inverter's transfer switch, then I presume that in "normal"
(meaning grid is up) mode, the transfer switch is configured to allow
the "protected load" (a.k.a. critical load panel or backed-up panel) to
feed directly back to the main grid panel, in order to maintain selling
to the utility. The Magnum is fed by another breaker in the main grid
panel, in order to maintain battery charging. When the grid goes down,
the transfer switch is manually switched to allow the grid-tied
inverter(s) to directly feed the protected load panel, rather than the
main grid panel. The output of the Magnum is capable of being backfed
through the AC load output to function as a battery charger.<br>
<br>
The Magnum has to be able to input on the AC load output in order to
utilize the AC output of the grid-tied inverter(s). The grid-tied
inverter(s) can't feed the main grid panel, as they would shut off
during a grid outage. And the Magnum's AC input can't feed off of the
protected loads panel, as its output also feeds that panel and it would
then be trying to feed itself.<br>
<br>
Am I even close here? It's enough to give an aging solar bozo a
headache. I would appreciate a wiring diagram and clarification as to
how such a system would be configured. And then there's the question of
why it would even be done this way, using a battery-based inverter only
for backup and a separate inverter(s) for grid-tie. What are the
advantages to this approach over simply using a battery-based
grid-interactive inverter, such as a GVFX, Radian or XW?<br>
<br>
Thank you,<br>
Allan<br>
<br>
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<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a moz-do-not-send="true"
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face="Times New Roman, Times, serif"><u>Allan@positiveenergysolar.com</u></font></a></small><font
face="Times New Roman, Times, serif"><br>
<span style="font-size: 10pt;">NABCEP Certified Photovoltaic Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
<b>Positive Energy, Inc.</b><br>
3201 Calle Marie<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a moz-do-not-send="true" href="http://www.positiveenergysolar.com/"
target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font>
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<span style="font-size: 10pt;"><br>
</span> </div>
<br>
On 9/2/2011 6:20 PM, Brian Faley wrote:
<blockquote
cite="mid:29F6EE1B9DE8E648A7615A315B840161C9E58B@MAGNUMMAIL.MagnumEnergy.local"
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<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">Hi Allen,<o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">I’ll try to
describe the typical AC coupled system as well as I can.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">In such a
system, a NON-grid tied battery based inverter (i.e. Magnum MS PAE) is
connected as a backup inverter, only supplying AC power to consumer’s
loads when the grid is down. The micro inverter(s), or string inverters
are connected on the load side of the inverters transfer switch, in
parallel with the inverter output so they see AC grid power (when
available) or inverter power when the grid goes down. The micro
inverters / string inverters in such a system are called AC coupled
inverters because the point of coupling is the AC system rather than
the DC system. This allows the battery based inverter to provide the
grid reference to the AC coupled grid-tied inverters when the utility
power is not present – Backup mode. In that mode the inverter will form
the reference for the grid tied inverters and any surplus power
supplied by the grid-tied inverters that is not being consumed by AC
loads will charge the battery of the inverter. In this inverter mode,
once the battery is full, the inverter senses it and shifts the
inverter frequency by .5hz to force the grid tied inverters off,
keeping them from exporting power, thereby stopping the battery from
overcharging. <o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">On a large
system, a DC diversion load is usually added in parallel with the
battery to reduce the on/off cycling of the grid tied inverters, which
once the frequency shift happens, will try to reconnect every five
minutes without it. <o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">Using the
frequency shift method only is rather crude, because it essentially is
a bang/bang controller – off or on. Its not a matter of our lack of
confidence in the approach, the question is do you want the battery
voltage swinging around by several volts. In a DC diversion mode
system, the surplus energy from the grid tied inverters can be put to
work as a useful dump load rather than just off lining several kw of
PV. <o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">We had a
white paper describing the AC couple mode. I’ll see what we can do to
make it more widely available, since the interest in such systems seems
to be increasing.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<div>
<p class="MsoAutoSig"><font color="navy" face="Times New Roman"
size="3"><span style="font-size: 12pt; color: navy;">Brian Faley<o:p></o:p></span></font></p>
<p class="MsoAutoSig"><font color="navy" face="Times New Roman"
size="3"><span style="font-size: 12pt; color: navy;">Chief Engineer<o:p></o:p></span></font></p>
<p class="MsoAutoSig"><font color="navy" face="Times New Roman"
size="3"><span style="font-size: 12pt; color: navy;">Magnum Energy<o:p></o:p></span></font></p>
<p class="MsoAutoSig"><st1:street w:st="on"><st1:address w:st="on"><font
color="navy" face="Times New Roman" size="3"><span
style="font-size: 12pt; color: navy;">2111 W Casino Rd</span></font></st1:address></st1:street><font
color="navy"><span style="color: navy;"><o:p></o:p></span></font></p>
<p class="MsoAutoSig"><st1:place w:st="on"><st1:city w:st="on"><font
color="navy" face="Times New Roman" size="3"><span
style="font-size: 12pt; color: navy;">Everett</span></font></st1:city><font
color="navy"><span style="color: navy;">, <st1:state w:st="on">WA</st1:state>
<st1:postalcode w:st="on">98204</st1:postalcode></span></font></st1:place><font
color="navy"><span style="color: navy;"><o:p></o:p></span></font></p>
<p class="MsoAutoSig"><font color="navy" face="Times New Roman"
size="3"><span style="font-size: 12pt; color: navy;">425-353-8833<o:p></o:p></span></font></p>
<p class="MsoAutoSig"><st1:personname w:st="on"><font color="navy"
face="Times New Roman" size="3"><span
style="font-size: 12pt; color: navy;"><a moz-do-not-send="true"
class="moz-txt-link-abbreviated" href="mailto:bfaley@magnumenergy.com">bfaley@magnumenergy.com</a></span></font></st1:personname><font
color="navy"><span style="color: navy;"><o:p></o:p></span></font></p>
</div>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"><o:p> </o:p></span></font></p>
<div
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<div>
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color="black" face="Times New Roman" size="3"><span
style="font-size: 12pt; color: windowtext;">
<hr tabindex="-1" align="center" size="2" width="100%"> </span></font></div>
<p class="MsoNormal"><b><font color="black" face="Tahoma" size="2"><span
style="font-size: 10pt; font-family: Tahoma; color: windowtext; font-weight: bold;">From:</span></font></b><font
color="black" face="Tahoma" size="2"><span
style="font-size: 10pt; font-family: Tahoma; color: windowtext;"> <a
moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>]
<b><span style="font-weight: bold;">On Behalf Of </span></b>Allan
Sindelar<br>
<b><span style="font-weight: bold;">Sent:</span></b> Friday,
September 02, 2011 4:45 PM<br>
<b><span style="font-weight: bold;">To:</span></b> RE-wrenches<br>
<b><span style="font-weight: bold;">Subject:</span></b> Re:
[RE-wrenches] AC Coupling</span></font><font color="black"><span
style="color: windowtext;"><o:p></o:p></span></font></p>
</div>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt;">Brian,<br>
Could you speak a bit more to this, please? My understanding is that
the need with a string (or, I suppose, micro-) inverter and a
battery-based inverter is for a way to disconnect full batteries from
being overcharged when the grid is down and sell is disabled. The SMA
approach is to shift frequency to reduce string inverter output. I
thought that the battery-based (Outback, Magnum) approach is to use a
contactor to open string inverter AC based on voltage (crude, but
effective). <br>
<br>
So what I understand is that the PAE inverters shift frequency: do you
mean it simulates the shift that a <st1:place w:st="on"><st1:placename
w:st="on">Sunny</st1:placename> <st1:placetype w:st="on">Island</st1:placetype></st1:place>
would do? And if so, why is a diversion load recommended, and how is it
configured into the system? And where can we read more about how this
is designed to work?<br>
Thank you,<br>
Allan<br>
<o:p></o:p></span></font></p>
<div>
<p class="MsoNormal"><b><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt; font-weight: bold;">Allan
Sindelar</span></font></b><br>
<font size="2"><span style="font-size: 10pt;"><a
moz-do-not-send="true" href="mailto:Allan@positiveenergysolar.com"><font
color="#000099"><span style="color: rgb(0, 0, 153);">Allan@positiveenergysolar.com</span></font></a></span></font><br>
<font size="2"><span style="font-size: 10pt;">NABCEP Certified
Photovoltaic Installer<br>
NABCEP Certified Technical Sales Professional<br>
<st1:state w:st="on"><st1:place w:st="on">New Mexico</st1:place></st1:state>
EE98J Journeyman Electrician<br>
<b><span style="font-weight: bold;">Positive Energy, Inc.</span></b><br>
3201 Calle Marie<br>
<st1:place w:st="on"><st1:city w:st="on">Santa Fe</st1:city>, <st1:state
w:st="on">New Mexico</st1:state> <st1:postalcode w:st="on">87507</st1:postalcode></st1:place><br>
<b><span style="font-weight: bold;">505 424-1112</span></b><br>
<a moz-do-not-send="true" href="http://www.positiveenergysolar.com/"
target="_blank">www.positiveenergysolar.com</a><u1:p></u1:p></span></font>
<o:p></o:p></p>
</div>
<p class="MsoNormal"><font color="black" face="Times New Roman"
size="3"><span style="font-size: 12pt;"><br>
On 9/2/2011 4:39 PM, Brian Faley wrote: <o:p></o:p></span></font></p>
<pre wrap=""><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">Hi Larry, <o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">Magnum MS PAE inverters do indeed shift the inverter output frequency<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">when the battery is full in order to disconnect grid-tied inverters used<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">in AC coupled systems. It was designed to work in conjunction with a DC<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">diversion load - which is recommended if the system is larger than a<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">couple panels.<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">Regards,<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;"><o:p> </o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">Brian Faley<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">Chief Engineer<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">Magnum Energy<o:p></o:p></span></font></pre>
<pre><st1:street w:st="on"><st1:address w:st="on"><font
color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">2111 W Casino Rd</span></font></st1:address></st1:street><o:p></o:p></pre>
<pre><st1:place w:st="on"><st1:city w:st="on"><font color="black"
face="Courier New" size="2"><span style="font-size: 10pt;">Everett</span></font></st1:city>, <st1:state
w:st="on">WA</st1:state> <st1:postalcode w:st="on">98204</st1:postalcode></st1:place><o:p></o:p></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;">425-353-8833<o:p></o:p></span></font></pre>
<pre><font color="black" face="Courier New" size="2"><span
style="font-size: 10pt;"><a moz-do-not-send="true"
href="mailto:bfaley@magnumenergy.com">bfaley@magnumenergy.com</a><o:p></o:p></span></font></pre>
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