<div dir="ltr">Hi Wrenches,<div><br></div><div>Jerry, I think you are correct, sma gear all around would be best. This will be my recommendation but I am sensitive to this substantial cost.</div><div>Dave, if I add the second Sunny Island, I don't think I will be throttled back because the transfer relays are rated for 60A. This should pass the full current of the output of the Fronius, which is 41.7A. My concern is more during backup mode, if the Sunny Islands could "trick" the Fronius into staying on line. I would add either load dump relay control or an AC interrupt relay to knock the Fronius off-line if the batteries were full, in addition to the frequency shift control that the Sunny Island offers.</div>
<div><br></div><div>Thanks for the input, I'll shoot for all SMA gear.</div><div><br></div><div>Thanks</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Jul 3, 2014 at 9:23 AM, Dave Click <span dir="ltr"><<a href="mailto:daveclick@fsec.ucf.edu" target="_blank">daveclick@fsec.ucf.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Mac, that Island interconnects with a max 70A 1P breaker (6.7kW
continuous), so unless they have a constant critical load draw or
the Fronius is massively oversized, you probably don't want to AC
couple the Fronius. The 5048 is also able to output a continuous
5000W only when it's cooler than 77F and it derates above that
(4500W at 95F, for example). I don't believe its surge ratings apply
to the AC2 output back into the utility but they probably wouldn't
be enough, anyway. I think that whenever the Fronius output reached
about 6000W, the SI would shift its frequency to switch the Fronius
off. Cheapest may be along the lines of your first option-- not sure
what the PV stringing is like but maybe you could move a string or
two off the Fronius and put it onto a new Sunny Boy with an
autoformer. Since I imagine this system doesn't have PV WIRE on the
module leads or home runs, officially I'd recommend a classic Sunny
Boy. Then leave the Fronius as-is. <br>
<br>
Unless of course the customer thought they were buying a system with
the full 10kW supplying critical loads when the utility is down...
then the original contractor is stuck with buying the second SI they
should have installed in the first place.<br>
<br>
DKC<div><div class="h5"><br>
<br>
<br>
<div>On 2014/7/3, 10:46, Mac Lewis wrote:<br>
</div>
</div></div><blockquote type="cite"><div><div class="h5">
<div dir="ltr">Hello wrenches,
<div><br>
</div>
<div>I wanted to run this scenario by the forum. I have spoken
with SMA about this, but want some other opinions.</div>
<div><br>
</div>
<div>We were recently contracted by a fellow solar company to do
some warranty work for them out of town on a Sunny Island
system that they had installed about 5 years ago. It was VERY
poorly implemented originally and was never installed as SMA
intended. In fact, during a small power outage, the only
loads that never came back on after the utility was back on
line were the loads in the critical load panel. Oops. </div>
<div><br>
</div>
<div>Anyway, our job is to get it working properly for the least
amount of cost possible. They have a Fronius IG Plus 10.0 fed
into a 400A service panel. The Sunny Island 5048 AC Input
also comes off of this panel and feeding a 120V only critical
load panel. Please note that there is no solar fed into the
AC output side of the Sunny Island, because there is not
120/240 available and thus there is no possible way for this
system to utilize the solar while the grid is not present.</div>
<div><br>
</div>
<div>I see two options (but there may be more): pull out
Fronius, put in Sunny Boy inverters and an autoformer, wire
properly. Another option is to add second Sunny Island and
try to AC couple the Fronius with the two Sunny Islands. The
second option is less expensive overall, but I'm hesitant to
rely on AC coupling with the Fronius.</div>
<div><br>
</div>
<div>I'd appreciate any thoughts on this.</div>
<div><br>
</div>
<div>Thanks</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br clear="all">
<div><br>
</div>
-- <br>
<div><br>
</div>
<div><font color="#305A78" face="'times new roman', serif"><br>
</font></div>
<div><br>
</div>
Mac Lewis<br>
<br>
<span><b><font face="Arial, Helvetica, sans-serif" size="3">
<p align="left"><font color="#000000" face="Verdana,
Arial, Helvetica, sans-serif"><span style="font-size:small"><span style="font-family:arial;font-weight:normal;color:rgb(48,90,120)"><font face="'times new roman', serif">"Yo solo sé
que no sé nada." </font><span style="font-weight:700;color:rgb(104,104,104)"><font face="'times new roman', serif">-Sócrates</font></span></span></span></font></p>
</font></b></span>
</div>
</div>
<br>
<fieldset></fieldset>
<br>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div><br></div><div><font color="#305A78" face="'times new roman', serif"><br></font></div><div><br></div>Mac Lewis<br><br><span style="font-family:'Times New Roman';font-size:medium;color:rgb(255,153,0)"><b><font face="Arial, Helvetica, sans-serif" size="3"><p align="left">
<font color="#000000" face="Verdana, Arial, Helvetica, sans-serif"><span style="font-size:small"><span style="font-family:arial;font-weight:normal;color:rgb(48,90,120)"><font face="'times new roman', serif">"Yo solo sé que no sé nada." </font><span style="font-weight:700;color:rgb(104,104,104)"><font face="'times new roman', serif">-Sócrates</font></span></span></span></font></p>
</font></b></span>
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