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<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>Ray, </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>I think a few people have already chimed in. You can't use a
balancing transformer because in fact you already have a balancing transformer.
Mine is on the pole next to my house. Some are planted in the front or rear
yard, etc.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>If you have an outback X-240, now you sorta have two in
parallel (one little 4kw unit and one 25kw or 50kw version), that is not likely
a good idea.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>Another thing to note, if the first outback sells a few
hundred watts, it wakes up the other sleeper to help. I can't remember the exact
figure, so I looked it up. Each GVFX3648 can sell about 3300 watts, and using
the Power Save feature set P01 (the master to 0 [zero] and set P02 (the slave)
to 0 for, I guess, sell all the time, 1 for start to help on or before 15 Amps
AC, 2 for start to help on or before 24 Amps. Maybe even a setting of 3 would
delay it even more??? I am not sure. In my home system I only have one GVFX
inverter and one XW inverter, so I can't try it to be sure.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>For the sharp modules, I would use a clamp on dc meter to
measure amps from each string at the combiner during full sun and verify that
all strings are a) equal, b) high enough (shoot for 80% of nameplate for
</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>instance). I have found some strings to be lacking and moved
modules around to get an optimized array. With the string breaker off, you can
measure the individual pv module performance (kinda) with an incandescent bulb
and some test leads in the junction box [or add a dc switch for MC cable]. Of
course, ground mounted arrays are worth their weight in silver for this aspect
alone.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>Maverick</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=199402502-06012012><FONT color=#0000ff
size=2 face=Arial>P.S. <SPAN class=199402502-06012012><FONT color=#0000ff size=2
face=Arial>Of course, I think of some weird things at times... with one
inverter, if you have local loads on the red leg, while selling on the black
leg, doesn't the utility transformer run your power back through their
meter $$$? Hopefully, the meter zeros out this cross flow... I
digress...</FONT></SPAN></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>Ray
Walters<BR><B>Sent:</B> Thursday, January 05, 2012 3:34 PM<BR><B>To:</B>
RE-wrenches<BR><B>Cc:</B> Levi, Dean<BR><B>Subject:</B> Re: [RE-wrenches] DC to
AC derate<BR></FONT><BR></DIV>
<DIV></DIV>I have a related question to this. Does setting up a pair of Outback
GVFXs with the balancing transformer and allowing one inverter to go to sleep at
lower AC output improve efficiency? It seems we would be reducing
electronic loads, but adding transformer losses. Any comments? I
have a recently commissioned double Outback system with 200 AH @48v battery
bank. He's reporting efficiency at 77% DC in to AC out. I'd love to
improve that, as his aging array of Sharp modules seems to be under performing
as well, (4.08 KW STC rated, 3 Kw actual out) I haven't gone back
and done testing with my insolation meter, so I'm not sure exactly what is
happening, but his overall efficiency (STC rated to AC out) is only 56%
.<BR><BR>Ray<BR><BR>On 1/4/2012 7:55 PM, Maverick Brown [Maverick Solar] wrote:
<BLOCKQUOTE cite=mid:A4F08B3A7C2746219FA24FD632D8CB46@MSE002 type="cite">
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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></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></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></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></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></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"
moz-do-not-send="true">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></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></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></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></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></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></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=683282302-05012012></SPAN> </DIV><BR>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> <A class=moz-txt-link-abbreviated
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</A>
[<A class=moz-txt-link-freetext
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</A>]
<B>On Behalf Of </B><A class=moz-txt-link-abbreviated
href="mailto:boB@midnitesolar.com">boB@midnitesolar.com</A><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>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></BLOCKQUOTE></BODY></HTML>