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<DIV dir=ltr align=left><SPAN class=796553518-20102009><FONT color=#0000ff
size=2 face=Arial>Thanks Kent. And so I understand more clearly, in the case of
2 SIs as you describe, each SI has it's own battery bank, and the solar would be
split between the two.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=796553518-20102009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=796553518-20102009><FONT color=#0000ff
size=2 face=Arial>Considering the charging capacity of the SI, what would you
say is the largest battery bank size for each SI to insure an effective "C"
value?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=796553518-20102009></SPAN> <BR><SPAN
lang=en-us><FONT size=2 face=Arial>Mark Frye</FONT></SPAN> <BR><SPAN
lang=en-us><FONT size=2 face=Arial>Berkeley Solar Electric Systems</FONT></SPAN>
<BR><SPAN lang=en-us><FONT size=2 face=Arial>303 Redbud Way</FONT></SPAN>
<BR><SPAN lang=en-us><FONT size=2 face=Arial>Nevada City, CA
95959</FONT></SPAN> <BR><SPAN lang=en-us><FONT size=2 face=Arial>(530)
401-8024</FONT></SPAN> <BR><SPAN lang=en-us></SPAN><A
href="http://www.berkeleysolar.com/"><SPAN lang=en-us><U><FONT color=#0000ff
size=2 face=Arial>www.berkeleysolar.com</FONT></U></SPAN></A><SPAN
lang=en-us><FONT size=2 face=Arial> </FONT></SPAN> </DIV>
<DIV> </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>Kent
Osterberg<BR><B>Sent:</B> Tuesday, October 20, 2009 11:10 AM<BR><B>To:</B>
glenn.burt@glbcc.com; RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] AC
Coupled Re-visited<BR></FONT><BR></DIV>
<DIV></DIV>In off-grid mode the Sunny Island uses frequency shift power control
to reduce the output of the Sunny Boy inverters and thereby regulate the battery
voltage. At some frequency shift (+1, or 2, or 3 Hz, I'm not sure) the
output of the SB is reduced by 100%. It's proportional so that 1/2 as much
frequency shift gives a 50% reduction in the SB output. To keep clocks
accurate, the Sunny Island later shifts the frequency a negative amount, but the
SB inverters ignore that. For a grid backup system, a RS-485 cable is
required so the Sunny Island can activate (or deactivate) the frequency shift
power control capability of the SB.<BR><BR>You need to stack two SI inverters to
get 240-vac, but that will allow you to have a 10-kW of grid backup power with
up to 12-kW of solar. If you need more, you can stack four of SI
inverters.<BR><BR>Kent Osterberg<BR>Blue Mountain Solar, Inc.<BR><BR><BR>Glenn
Burt wrote:
<BLOCKQUOTE cite=mid:002301ca51aa$c79a7880$56cf6980$@burt@glbcc.com
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<DIV class=Section1>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Our
installations of Sunny Islands (SI) with Sunny Boys (SB) have always used the
recommended RS-485 communications between all units involved. This with
reprogramming the SB’s to be able to switch to off-grid mode per the SI
instructions allows a more integrated system.<O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"><O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">We
have had problems with the OB PSX-240 and stepping up the 120 to 240 for the
crit load panel (where the SB’s connect) when the site has slightly high AC
voltages. The SB pushes the existing ACV higher, then it goes out of UL spec
& disconnects. Also the SB is now sensitive to imbalance on L1 & L2
because of the neutral sensing – we had a customer where the SB was
disconnecting due to this as well…<O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"><O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">I
thought the freq shifting was to allow other non-SMA inverters to be
controlled when batteries were full?<O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Where
is the SMA rep on this list?<O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"><O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">-Glenn<O:P></O:P></SPAN></P>
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<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Tahoma','sans-serif'; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'Tahoma','sans-serif'; FONT-SIZE: 10pt"> <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>Kirpal Khalsa<BR><B>Sent:</B> Tuesday, October 20, 2009
12:05 PM<BR><B>To:</B> RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] AC
Coupled Re-visited<O:P></O:P></SPAN></P></DIV>
<P class=MsoNormal><O:P></O:P></P>
<P class=MsoNormal>Greetings......it is my understanding that the Sunny Island
coupled with Sunny Boys is able to taper charge in an AC coupled system as the
2 inverters are able to communicate with each other and the Sunny Island
alters the frequency input of the Sunny Boys and lowers the total output of
the Sunny Boys to match the needs of the battery bank....this is SMA's method
of not using their "charger"....they simply alter the amount of available AC
input into the AC to DC converter present in the Sunny Island.....This logic
is what encouraged me to select SMA's for an AC coupled design rather than
mixing brands of battery-less and battery based inverters.....in a mixed brand
scenario there is no communication other than an on/off command so no
regulation is available.....My understanding may be flawed--please correct me
if so....<BR>Another way for mixed brands to AC couple and provide some charge
"control" would be to have an AC dumpload on the AC input side of the battery
based inverter to suck up some of the excess power from the GT inverters so
not as much power is available for battery charging.....This dumpload would be
voltage based and in a mixed brand system would add more relays to the
mix...in many cases there may not be that many auxillary outputs available to
connect relays to.....<BR>I would like to see more GT inverter companies make
compatible battery based inverters......One idea is for micro inverters to be
paired with the battery based inverters and when less power was needed to
facilitate a taper charge one solar panel at a time could be switched
off......effectively providing a smaller available charge current to help with
the taper charging.....<BR><BR>-- <BR>Sunny Regards,<BR>Kirpal
Khalsa<BR>NABCEP Certified Solar PV Installer<BR>Renewable Energy
Systems<BR><A href="http://www.oregonsolarworks.com"
moz-do-not-send="true">www.oregonsolarworks.com</A><BR>541-218-0201
m<BR>541-592-3958 o<O:P></O:P></P>
<DIV>
<P class=MsoNormal><BR>On Tue, Oct 20, 2009 at 8:34 AM, Mick Abraham <<A
href="mailto:mick@abrahamsolar.com"
moz-do-not-send="true">mick@abrahamsolar.com</A>> wrote:<O:P></O:P></P>
<P style="MARGIN-BOTTOM: 12pt" class=MsoNormal>Hi, All~<BR><BR>On an AC
coupled system as Jeff describes, the "battery charge circuitry" on the
battery based inverter is not even participating. <BR><BR>A straight pure sine
inverter...with no charger function built in...would also "charge" the battery
if AC coupled to a SunnyBoy with no grid available. The "charge" is just the
inverter's way of dealing with back EMF.<BR><BR>I agree that better control
over that "recharge" is an important area; I hope somebody is working on that.
It's true that the "wild card recharge" only occurs if grid goes away but as
Jeff mentions, it only takes a few times of crummy end of charge management to
ruin a nice set of sealed batteries.<BR><BR clear=all>Mick Abraham,
Proprietor<BR><A href="http://www.abrahamsolar.com" target=_blank
moz-do-not-send="true">www.abrahamsolar.com</A><BR><BR>Voice:
970-731-4675<BR><BR><O:P></O:P></P>
<DIV>
<DIV>
<DIV>
<P class=MsoNormal>On Tue, Oct 20, 2009 at 9:21 AM, Jeff Yago <<A
href="mailto:jryago@netscape.com" target=_blank
moz-do-not-send="true">jryago@netscape.com</A>>
wrote:<O:P></O:P></P></DIV></DIV>
<BLOCKQUOTE
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<DIV>
<DIV>
<DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">We have
completed several totally different AC coupled systems using different
inverters, due to large ground mounted arrays that had to be located a great
distance from inverter-battery-generator-grid BAS, which are working just
fine even with the mis-match of inverter brands. The SunnyBoy seems to
not care what its connected to or how, as it just keeps doing what it does
and if a relay cuts off its connection to the grid when the battery voltage
goes high then it just waits and re-connects when the grid is back or the
battery voltage drops.<O:P></O:P></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt"><O:P></O:P></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">What I am
bothered by is the need to custom design a power relay circuit on each
project which takes lots of fine-tuning of setpoints to get everything
to work correctly. If you have not done one the problem is simple -
when you backfeed the AC output from a remote grid-tie inverter "through"
the AC side of a battery based inverter, everything works great and the
solar AC just passes straight through the sub-panel, back throught the
battery inverter, back into the grid. However, when the grid is
down and the battery-inverter is no longer receiving (or sending) power from
the grid, for some reason I cannot begin to understand, any AC being fed
from the solar inverter goes straight into battery charging with absolutely
no limit on charge rate or charge limit, and if you do not add a relay to
dis-connect or shut-down the solar inverter you can quickly destroy a bank
of AGM batteries if there are no major system loads as it just keeps
charging and charging.<O:P></O:P></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt"><O:P></O:P></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">I am not an
electronics engineer, but if the battery is being charged by the battery
charger built into the inverter, I just do not see why the same battery
charger suddenly has no clue that the battery is being overcharged when its
now receiving AC power from a different source. I think with larger
and larger arrays being installed as module costs fall, higher DC array
string voltges to reduce wire costs, and more people worried about grid
reliability, there would be a good market niche for an inverter that can
properly charge a battery bank regardless of which way the AC power comes
into the charger section. Whats the
problem?<O:P></O:P></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt"><O:P></O:P></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">Jeff
Yago<O:P></O:P></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">DTI
Solar<O:P></O:P></SPAN></P></DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt"><BR> <O:P></O:P></SPAN></P>
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