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Just reading up on Magnum's new AC load diversion controller. It
looks like the best option at this point, it provides AC load
diversion so you can use AC loads not DC resistors, and it
communicates with the inverter, so the system has both 3 stage temp
compensated battery charging, and has 2 fail safes, because Magnum
inverters can do the frequency shift method to turn off the GT
inverters as well.<br>
Anyone try this, or have any feed back/ comments?<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
<div class="moz-cite-prefix">On 8/21/2015 7:45 AM, Starlight Solar
Power Systems wrote:<br>
</div>
<blockquote
cite="mid:3C07F25A-BD7D-4967-8AAF-B368A646539C@starlightsolar.com"
type="cite">
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Ray,
<div class=""><br class="">
</div>
<div class="">I’m curious about what you mean by not doing a 3
stage charge. While PV charging in coupled mode (off grid), the
battery will reach your absorption set point. Is this triggering
the GT inverters to shut off or does the battery inverter absorb
timer run at all? I would think the absorb timer should run
until the array current produced is more than being consumed and
then the the GT shuts off.</div>
<div class=""><br class="">
</div>
<div class="">Just a wild idea here but if you could calculate the
AH needed to reach 100% SoC after the GT inverters shut down, a
separate PV array and charge controller would stay online to
finish the charge. No wasted energy to dump loads and the
customer has more usable power from the system. This may cost
more than going to a dump load though.</div>
<div class=""><span style="orphans: 2; text-align: -webkit-auto;
widows: 2;" class=""><br class="">
</span></div>
<div class=""><span style="orphans: 2; text-align: -webkit-auto;
widows: 2;" class="">Larry </span></div>
<div class="">
<br class="">
<div>
<div class="">On Aug 20, 2015, at 10:56 PM, Ray Walters <<a
moz-do-not-send="true" href="mailto:ray@solarray.com"
class="">ray@solarray.com</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type" class="">
<div bgcolor="#FFFFFF" text="#000000" class=""> Hi Folks;<br
class="">
<br class="">
I've done more research on the whole AC coupled issue, and
one flaw I found with both the Sunny Island and the Radian
is that they can't really do a full 3 stage charge for the
batteries in off grid mode.<br class="">
They detect that the batteries are full and disconnect the
AC coupled GT inverters, but this is about as subtle as
the very early charge controllers, and amounts to 1 stage
charging. This is fine for temporary outages, and when
the grid comes back, the batteries get a good 3 stage
charge. But these folks are really wanting a design that
could be taken off grid permanently. Also as you my
recall, the GT PV system is Enphase, so we can't use the
more sophisticated controls that SMA offers for the Sunny
boys. <br class="">
I hate to say it, but I might be back to a diversion load
with PWM controller. Not elegant, but we could get 3
stage charging. <br class="">
Every time I look at AC coupled setups, I just want to
start over with charge controllers. <br class="">
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
<div class="moz-cite-prefix">On 8/17/2015 9:39 PM, Mac
Lewis wrote:<br class="">
</div>
<blockquote
cite="mid:CAOABG4_E0OWuKThmiVmhtvkfY0XDHO7Kf3+A8-=EKVvPn_ZX0g@mail.gmail.com"
type="cite" class="">
<div dir="ltr" class="">Hi Ray,
<div class=""><br class="">
</div>
<div class="">With that size grid-tied system, you
would want to use a battery based inverter(s) near
the (6.7/0.8) 8000W range. </div>
<div class=""><br class="">
</div>
<div class="">The frequency shift of the Sunny Islands
will work with kicking out the enphase inverters but
you wouldn't get the same output ramping that it
would offer if it was a Sunny Boy grid-tied
inverter. The Sunny Island can effectively solve
your generator backfeeding because there is a
reverse current sensor that will disconnect the AC
input at whatever level you want, 50 mA is default I
think. You may need to give the Sunny Island
generator start control for this however.</div>
<div class=""><br class="">
</div>
<div class="">You can read about it here on page 137.</div>
<div class=""><br class="">
</div>
<div class=""><a moz-do-not-send="true"
href="http://files.sma.de/dl/15216/SI4548-6048-US-BE-en-21W.pdf"
class="">http://files.sma.de/dl/15216/SI4548-6048-US-BE-en-21W.pdf</a><br
class="">
</div>
<div class=""><br class="">
</div>
<div class="">You'll need to give the Sunny Island a
digital signal that tell it whether its connected to
a generator or a grid as outlined in the manual. </div>
<div class=""><br class="">
</div>
<div class=""> This is where the Radian is nice
because it has two AC Input terminals.</div>
<div class=""><br class="">
</div>
<div class="">Sounds like an interesting project.</div>
<div class=""><br class="">
</div>
<div class="">Good Luck.</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
</div>
</div>
<div class="gmail_extra"><br class="">
<div class="gmail_quote">On Mon, Aug 17, 2015 at 8:36
PM, Jerry Shafer <span dir="ltr" class=""><<a
moz-do-not-send="true"
href="mailto:jerrysgarage01@gmail.com"
target="_blank" class="">jerrysgarage01@gmail.com</a>></span>
wrote:<br class="">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<p dir="ltr" class="">I cant see this working well
without some battery based inverter<span
class="HOEnZb"><font class="" color="#888888"><br
class="">
Jerry</font></span></p>
<div class="HOEnZb">
<div class="h5">
<div class="gmail_quote">On Aug 17, 2015 10:10
AM, "Ray Walters" <<a
moz-do-not-send="true"
href="mailto:ray@solarray.com"
target="_blank" class="">ray@solarray.com</a>>
wrote:<br type="attribution" class="">
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">HI Esteemed
Wrenches:<br class="">
<br class="">
I am consulting on a system I have never
seen, that consists of a 6.7Kw Enphase
roof mounted system, and 2 backup
generators. Each generator has an
automatic 200 amp transfer switch to back
up its own 200 amp panel. Both 200 amp
panels are fed by a 400 amp service from
the grid.<br class="">
The Enphase PV backfeeds a subpanel in
another building which then is fed by a 2
pole 60 amp breaker in one of the 200 amp
panels.<br class="">
Currently they are having issues with the
generators kicking out because of the
Enphase inverters. That part I
understand: you can't backfeed a
generator, or its voltage regulation
freaks out.<br class="">
<br class="">
Now we get to the fun part: they want to
create a third critical load subpanel with
loads selected from both 200 amp panels to
be powered by batteries and an inverter.<br
class="">
I am considering the Sunny Island since it
makes the most sense with its ability to
signal the Enphase inverters to shut off
when the batteries are full. I also see
this as a partial solution to the
generator issue, since normally the
Enphase will be connected to the output
side of the Sunny Island. However, when
the generator is used to charge, we will
be back to directly coupling the generator
output to the Enphase.<br class="">
<br class="">
Here are some possible solutions I'm
considering:<br class="">
1) Use a separate charger for the
generator so that it will only feed DC to
the batteries, and not be AC coupled.<br
class="">
2) convert the PV back to DC with charge
controllers, but that would involve
ditching and adding another conduit run
between buildings.<br class="">
3) Put the Enphase PV on a relay that
would disconnect the PV when charging with
the generator.<br class="">
4) Something I haven't thought of that one
of you clever folks can suggest......<br
class="">
<br class="">
As always, thanks in advance for all you
responses,<br class="">
<br class="">
-- <br class="">
R.Ray Walters<br class="">
CTO, Solarray, Inc<br class="">
Nabcep Certified PV Installer,<br class="">
Licensed Master Electrician<br class="">
Solar Design Engineer<br class="">
<a moz-do-not-send="true"
href="tel:303%20505-8760"
value="+13035058760" target="_blank"
class="">303 505-8760</a><br class="">
<br class="">
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