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<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>Please use the 90% of the CEC or PTC rating of the PV module
at most.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>Among several systems that I monitor daily, I have an
example 11.760kw (STC) system that has a 500Ah battery bank and it
peaks at 77-80% of the STC rating each day.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>Peak is defined as the top of the bell curve that forms
from the graphing watts output versus nameplate watts.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>If I use the CEC rating (10.54kw), it peaks at 86-90% of the
CEC rating each day.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>If I go to the CEC list and copy & paste into a
spreadsheet and enter the values for the STC versus PTC, I <EM>might</EM>
find I would loose 10% (or more) in the PV rating.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial><A
href="http://www.gosolarcalifornia.org/equipment/pv_modules.php">http://www.gosolarcalifornia.org/equipment/pv_modules.php</A> (go
ahead, find your modules and divide PTC by Nameplate).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>I also have a grid-interactive system that has a very large
battery bank (2600Ah @ 48V, with 9kw STC Array) and it only has a peak
efficiency rating of 69% because of the load of the batteries. The larger
the battery bank, the happier customers are for outage situations, but the
larger the battery bank, the more current goes into "Floating" the batteries
during selling. For that system, I may lower "Grid Support/SellRE" and use Auto
EQ to keep the batteries fresh...</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>Anyway, keep in mind that you cannot simply
assume:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>12kw Array x 6 hours of sun = 72kwh of generation each
day. The brand of PV, the size of the battery bank and even the charge
controller's Absorb & Float settings can greatly reduce what the
inverter thinks it can sell. With multiple inverters and charge controllers it
gets even more complicated (worse).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012></SPAN><SPAN
class=683282302-05012012></SPAN><SPAN class=683282302-05012012><FONT
color=#0000ff size=2 face=Arial>Good luck,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial>Maverick</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV><BR>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>boB@midnitesolar.com<BR><B>Sent:</B> Wednesday, January 04, 2012 5:14
PM<BR><B>To:</B> RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] DC to AC
derate<BR></FONT><BR></DIV>
<DIV></DIV>On 1/4/2012 3:01 PM, All Solar, Inc. wrote:
<BLOCKQUOTE cite=mid:B5CBE3E26B764CC9987DB55BA8FD7972@SrvcTagGV13VB1
type="cite">
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<STYLE></STYLE>
<DIV><FONT size=2 face=Arial>Wrenches,</FONT></DIV>
<DIV><FONT size=2 face=Arial>Once again I am trying to size a grid tie
w/battery system and I struggle a little with the efficiencies of
them.</FONT></DIV>
<DIV><FONT size=2 face=Arial>With PV Watts (v.1), is changing the DC to
AC derate an accurate method for getting the output?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Thanks in advance!</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Jeremy</FONT></DIV></BLOCKQUOTE><BR><BR>If you keep
the batteries charged to a voltage just above their resting
voltage,<BR>say, 52 volts for a 48V system, and the battery bank isn't too
large, (~225 A-hours,<BR>maybe a bit more), about 90% PV to grid AC
efficiency is in the ball park.<BR><BR>That's what we figured in the early days
of GFX inverters at OB. That's giving<BR>5% for the electronics and 5% for
keeping up the batteries.<BR>Different and/or more accurate information may have
come along since<BR>that time.<BR><BR>boB<BR><BR><BR><BR><BR><BR><BR><BR><BR>
<BLOCKQUOTE cite=mid:B5CBE3E26B764CC9987DB55BA8FD7972@SrvcTagGV13VB1
type="cite">
<DIV><FONT size=2 face=Arial> </FONT></DIV>
<DIV><FONT size=2 face=Arial>All Solar Inc.<BR>Jeremy and Amy
Rodriguez<BR>1463 M St<BR>Penrose, CO 81240<BR><A
href="http://www.asolarelectric.com"
moz-do-not-send="true">www.asolarelectric.com</A><BR>Phone 719-372-3808<BR>Fax
719-372-3804<BR>Email <A href="mailto:allsolar@scswifi.net"
moz-do-not-send="true">allsolar@scswifi.net</A><BR>Email <A
href="mailto:allsolar@live.com"
moz-do-not-send="true">allsolar@live.com</A></FONT></DIV><BR>
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