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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Whoa… I think the AC not starting is
only part of the problem and I’m not talking about technical issues.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>3.5 tons at 13 seer is going to have a
running kW of 4kW, give or take and on hot days that’s going to take the
battery to 50% in less then 5 hrs assuming no other loads are on. We’ve
recently looked into this for a customer that spontaneously added 3 ton 13 seer
unit to his part time off grid system without telling us until it was already
installed. Of course it was never part of the original design but
that’s an entirely different story. Thank heavens we have a good
relationship with this customer further bolstered by contract clearly detailing
what the system was designed to do.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>According to everything we can find and
the HVAC installer you need a minimum of 5 to 7.5 times the running current to
start an AC unit. A “hard start” capacitor will not help because
all it does is give the AC unit more amps to start but do not actually reduce
the starting surge. Apparently as AC’s age they can actually get
harder to start so these units help with that. I’ve not come across
the “soft start” you mention unless your talking about 3 phase
stuff.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The Xantrex XW4024 at this project will
not start his 3 ton unit. But of course, it’s not that
simple. This is a tiny off grid system with one string of L16’s.
When the AC attempts to start we observe the battery voltage dropping on the
fully charged battery bank to 21v while the kW reading on the XW never goes
past the mid 2’s. While this is happening the XW’s voltage drops
L-L voltage drops to 156v. The inverter does not fault out and only shows
a Low battery voltage error message. So my theory is the XW can’t
hold the 240 L-L during the surge which inherently reduces the surge thus self
limiting the AC unit and preventing the inverter from going into a fault mode.
But that’s just my guess. Xantrex technical did pick up the phone but they
were pretty puzzled why the inverter didn’t go into fault mode.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Our solution is to install a 17kW
generator and run the AC off the generator only. The generator and a
propane tank are a 100% solution and they were cheaper then adding inverters
and batteries which we were pretty sure had a pretty good chance of not being a
100% solution. Since it’s a rarely used off grid cabin the propane usage
wont’ be terrible.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>IMHO, Max, I suggest that you don’t
even try to run the AC off of the inverter or even think about adding a 2<sup>nd</sup>
one because it’s always going to be problematic.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Best,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Travis Creswell<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Ozark Energy Services<o:p></o:p></span></font></p>
<div>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Max Balchowsky<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, August 18, 2008 3:01
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] offgrid
system question</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<div id=yiv193486330>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Dear wrenches, going to look at a system installed by others and would
like some input from some of you with more off grid experience than I have ( 4
systems over the years). the system was put on a new home - off grid 20 sharp
ND123UJF panels 4 modules in series - 5 parrallel strings, 2460 total
array dc voltage. mppt 60-150 <span class=yshortcuts><span style='background-attachment:
scroll;background-position-x:0%;background-position-y:0%;cursor:hand'
id="lw_1219089563_0">charge controller</span></span>, 12 sun extender sealed <span
class=yshortcuts><span style='background:#DCEEFF'><span style='cursor:hand'
id="lw_1219089563_1">AGM batteries</span></span></span>, 305 AH at 12 vdc,
wired for 915 AH at 48 volt DC. The system is tripping off when the AC unit
trys to start - AC is comfortmaker 3.5 ton 13 seer. They say start up inrush is
104 amps (sounds high to me) and they put a DST 10 <span class=yshortcuts><span
style='cursor:hand' id="lw_1219089563_2">soft start</span></span> on the unit
(I think that's just a big capacitor). I haven't been on site yet but it sounds
to me that they just didn't design enough inverter capacity into the
system...... What are your thoughts?<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Max Balchowsky<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>SEE Systems<o:p></o:p></span></font></p>
</div>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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