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<p class=MsoNormal><span style='color:#1F497D'>Mark,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>You haven’t provided
enough information for the questions you’re asking. You have said nothing
about the customer’s load profile.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Did you install a Tri-Metric in
the system? CAH will allow you to estimate daily consumption. Otherwise, get
the customer to provide a load analysis, and compare it to the you did with
him/her when you designed the system.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Part of the likely problem is
that neither gennie or array will charge sufficiently. You didn’t say
what the charge amps is with the gennie, but I suspect it’s surprisingly
low, meaning a small degradation in charge efficiency substantially increases
charging time. The combination of a cheap portable generator and DR inverter(s)
is particularly prone to poor charging, as the DRs grab the peak of the gennie’s
waveform, and cheaper gennies provide adequate RMS voltage but poor peak
voltage. Check you peak voltage on the gennie under load – it needs to be
164V for full DC output. Low peak voltage often results in very low DC charging
current. This is covered in more detail in the sidebar on page 100 of the
June/July 09 HP article on generators.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>There are no cheap solutions for
your customer. For a no-cost solution, take 4 L16s out of the system, run one
string. The cheapest charging solution is a good-sized 5,000-6,500 W) 120/240V
inverter-generator, such as Honda or Yamaha. Don’t run the inverters at
max charge rate (70A on a DR2424 X 2 inverters is a C/5 rate, too hot for those
L16s). Otherwise add lots of array.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>We set C40s to 1.600 bulk, .900
float. The C40 only absorbs for two hours; this could also contribute.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;color:#1F497D'>Allan Sindelar<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;color:#1F497D'><a
href="mailto:Allan@positiveenergysolar.com">Allan@positiveenergysolar.com</a></span><span
style='font-size:11.0pt;color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;color:#1F497D'>NABCEP
Certified Photovoltaic Installer</span><span style='font-size:11.0pt;
color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;color:#1F497D'>EE98J
Journeyman Electrician</span><span style='font-size:11.0pt;color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><b><span style='font-size:11.0pt;color:#1F497D'>Positive
Energy, Inc.<o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-size:11.0pt;color:#1F497D'>3201 Calle
Marie<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;color:#1F497D'>Santa Fe, New
Mexico 87507<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;color:#1F497D'>505 424-1112<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;color:#1F497D'><a
href="http://www.positiveenergysolar.com/">www.PositiveEnergySolar.com</a></span><span
style='font-size:11.0pt;color:#1F497D'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
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<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>Mark
Frye<br>
<b>Sent:</b> Thursday, December 03, 2009 10:23 AM<br>
<b>To:</b> 'RE-wrenches'<br>
<b>Subject:</b> [RE-wrenches] Off-Grid Sizing Case<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Folks,</span>
<o:p></o:p></p>
<p><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>I have a
customer with a 3 year old system in northern CA:</span> <o:p></o:p></p>
<p><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>8 - Deka
370AH, 6V, 2x4 banks - 740Ah @ 24V</span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>2 - DR2424
120/240V series</span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>4 - EC-120-GL</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>1 - C40 CC</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>1 - 5000W, old
portable gas gen</span> <o:p></o:p></p>
<p><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>The problem
is increased gen runtime probally due to chronic undercharging.</span> <o:p></o:p></p>
<p><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Based on
estimated consumption in the home, I think he needs about 2X the PV to meet the
energy production needs in the summer (5 kWH/day)(30% DOD/day). But in order to
get C10 charging during the summer he would need 5X the PV?</span><o:p></o:p></p>
<p><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Money is and
issue. So what should I recommend:</span> <o:p></o:p></p>
<p><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>1 - Increase
PV 4X to 5X, add MPPT controller to get to a PV based system with gen support</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>2 - Get a 3K to
5K propane gen and and run as a gen based system with PV support</span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>3 -?</span> <br>
<span style='font-family:"Arial","sans-serif"'> </span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Mark Frye</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Berkeley Solar
Electric Systems</span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>303 Redbud Way</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Nevada
City, CA 95959</span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>(530) 401-8024</span>
<br>
<a href="http://www.berkeleysolar.com"><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>www.berkeleysolar.com</span></a><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span> <o:p></o:p></p>
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