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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hi Mick,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>We’re increasingly running into this “how big can
you go with battery-based grid-tie” question. Most of the hardware out
there was designed with modest residential systems in mind. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Outback is limited to 2 inverters max in grid-tie mode. 7.5kW.
(I’m really curious what Darryl is doing with his 12-stack. I suspect it’s
functional but not exactly in compliance with UL listings.)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>With Xantrex we can get to 3 inverters, 18kW.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>A Sunny Boy / Sunny Island stack can go to 4 Islands, 20kW.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Both Satcon and Princeton Inverters make 100kW battery-based,
grid-tie capable inverters. The Satcon runs a 240vdc battery pack…exciting!
Not sure about Princeton, but I believe it’s the same. Prices
for these large, more or less custom-built inverters is astronomical. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>And dammit, there’s nothing in between 20kW and 100kW! (A
least that I’m aware of.) And we get requests in the 30-50kW range pretty
regularly now.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The best advice I can offer: First off, it’s just
crazy to build such large battery packs for grid-tied systems. Batteries
have become very expensive over the past few years, and even the best aren’t
going to last more than 15-20 years. So build the client a modest 18-20kW
battery backup system to cover the really important stuff. (Security system,
critical lighting, communications, etc.) Put everything else on an auto-start
backup generator. The food isn’t going to spoil in the two minutes
it takes the backup system to roll up to speed, and if the big screen goes
blank for a couple minutes…well life is just tough sometimes. I usually
recommend propane as a backup fuel, it gets delivered and it doesn’t
spoil or evaporate with age. But for something this big you’ll probably
need to go to diesel.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Good Luck!<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Doug Pratt<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>DC Power Systems <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<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"'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Mick
Abraham<br>
<b>Sent:</b> Friday, August 06, 2010 4:18 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> [RE-wrenches] Advice needed on upsizing a battery & grid
interactive inverter stack<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Yo, Mechanics~<o:p></o:p></p>
<div>
<p class=MsoNormal><o:p> </o:p></p>
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<div>
<p class=MsoNormal>A client is considering a "biggest ever for me"
battery based power system. They will probably scale down their ambitions once
the cost realities settle in but for now they've asked me to look for battery
based inverter systems which can scale bigger than a triple stack of Xantrex
XW6048 inverters. Your advice would be welcomed. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>* The system must be split phase 120/240, not 3
phase. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>* Outback seems "out" because the inverter group
should handle backup battery recharge using grid or generator AC...and we also
want to sell excess PV power to the grid.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>* No cobbled together AC coupled systems would be considered
without a convincing way to feather the end of charge on the battery when the
grid is down...float & all. I don't want to go back to the days of clunky,
coarse battery "end of charge" care. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>* Sunny Island/Sunny Boy is in contention but I'm not keen
on having to stack in pairs to maintain the 120/240 three wire architecture. A
single Sunny Island failure would take down two of the yellow boxes. What is
the limit on stack-ability for Sunny Island?<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>* A battery sales rep suggested Satcon brand but I think
that's bogus advice. Satcon is pure grid intertie only, right?<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>***********************************************<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>So...there is your challenge de la semaine (challenge
of the week). Who builds an inverter system with Xantrex XW-like features only
bigger...much bigger? OR: who could supply the "Mother of Sunny
Island/Sunny Boy" system? Replies would be welcomed on the List
or off.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>The Wrench List is the Bomb!<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Mick Abraham, Proprietor<br>
<a href="http://www.abrahamsolar.com">www.abrahamsolar.com</a><br>
<br>
Voice: 970-731-4675<o:p></o:p></p>
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