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Kirk,<br>
I think there are a couple of subtleties that you're missing in your
post. All of the SW series that we installed in grid-tied mode prior
to Trace/Xantrex losing its 1741 listing - mostly Y2K installations
- are still in use legally, as they were grandfathered in. Once
Xantrex lost its listing and went to the GTI models (firmware rev.
4.10 and above), only with a GTI were they 1741, and the earlier
inverters couldn't be retrofit.<br>
<br>
So if Richard's customer's SW4048 is pre-GTI and is currently
legitimately utility-interactive, it could be argued that it's
grandfathered in. Of course, I'd avoid arguing anything that
esoteric with any governing body. <br>
<br>
But it's a moot issue anyway. Reviewing the other Wrenches'
suggestions, none advised continuing to use the SW as an interactive
inverter, but only as a charging source for a battery bank. One
Wrench suggested putting the SW's AC input on a weekly timer, which
is a good idea. Jay is correct that the SW was a terrible inverter
for grid-tie. One primary weakness of the SW series was that as long
as the grid was up, it tried to maintain float voltage to the
batteries continuously (this was the "lack of silent sell" issue).
This brought overall sell efficiency down to around 55%, as I
recall, rather than the 93+% efficiency of today's inverters. But if
the inverter is only being used as a charging source, it's not
selling and thus neither the poor efficiency nor the lack of a GTI
is relevant.<br>
<br>
Personally, I wouldn't get rid of the SW if the customer wants
battery backup. The inverters have proven generally reliable, and
this one is likely to last for decades as an occasional battery
charger. Plus it's already paid for, and does a good job as both a
battery charger and a backup inverter during outages. I'd use sealed
batteries to deal with the customer's maintenance concerns. The
Honda 3000i is a good choice at sea level, as the SW can hard-limit
the AC amp draw from an undersized generator and avoid overloading
it (and nuisance-tripping its output breaker). But note that the SW
can take up to about 5,200 watts from an AC source, and sealed
batteries prefer high charging C/rates, so you might want to use a
generator of around 6kW (at 120V) instead for better efficiency and
less runtime.<br>
<br>
Good thing Richard reposted - the second time got a bunch of us
responding. Kinda fun...<br>
<br>
Allan<br>
<br>
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<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com"><font
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<span style="font-size: 10pt;">NABCEP Certified Photovoltaic
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NABCEP Certified Technical Sales Professional<br>
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<b>Positive Energy, Inc.</b><br>
3201 Calle Marie<br>
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<b>505 424-1112</b><br>
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On 11/20/2011 4:33 AM, Kirk Herander wrote:
<blockquote cite="mid:000d01cca778$3f799af0$be6cd0d0$@vtsolar.com"
type="cite">
<pre wrap="">PS - Richard, does it have a Trace / Xantrex GTI interface installed? If
not, it's not code-legal to be tied to the grid anyway. Get rid of the 4048
whatever you do.
Kirk Herander
VT Solar, LLC
dba Vermont Solar Engineering
NABCEPTM Certified installer Charter Member
NYSERDA-eligible Installer
VT RE Incentive Program Partner
-----Original Message-----
From: <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>] On Behalf Of Richard L
Ratico
Sent: Friday, November 18, 2011 6:53 PM
To: <a class="moz-txt-link-abbreviated" href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>
Subject: Re: [RE-wrenches] Convert Grid Tie SW4048 to Backup System; Add New
Inverter, AC Coupled
Jay, Marv, Chris, Ray, Joel & Maverick,
Thanks tremendously for your input. Each of you provided interesting
suggestions, all of which I find thought provoking and helpful. I greatly
appreciate your taking the time to share your experience.
Dick
Solarwind Electric
--- You wrote:
We redid one in a very similar situation recently. In that case the
customer wanted super backup and so we put in Grid tie Outbacks and a
new battery bank, added modules, and kept the SWs as battery chargers
from the generator. He had the option with bypass switches to use the
SWs, if the Outbacks went out. This guy wanted a "keep the power going,
no matter what" system, but I can't claim that was optimal. The right
answer depends on what the customer wants.
I probably wouldn't trash everything though as Jay suggested, since the
existing modules are already racked and wired. (unless it's a bogus
install, then yep, salvage it all)
You could probably easily rewire the parallel 48 v sets of modules all
in series in 15 minutes in the combiner box to get the voltage up, and
use a small GT only inverter, too. I guess it would also depend on how
close the 2 different types of modules are in voltage or current, but it
doesn't have to be perfect; as these were modules headed to the scrap
heap otherwise.
In honor of modules that are well installed and still performing
correctly, I do try and reuse them. Being able to brag: "these have been
working for 30 years..." is great for the solar industry as a whole, but
only if it makes sense.
Ray
On 11/17/2011 5:51 PM, jay peltz wrote:
</pre>
<blockquote type="cite">
<pre wrap="">HI Richard,
I'll chime in, although you won't like it.
Dump the system and start over with a new battery less system and a genny
</pre>
</blockquote>
<pre wrap="">as
back up.
</pre>
<blockquote type="cite">
<pre wrap="">
Told you, you wouldn't like it.
The SW parts are basically gone and it was a terrible grid tied inverter
</pre>
</blockquote>
<pre wrap="">anyway.
</pre>
<blockquote type="cite">
<pre wrap="">The modules are usable but why at $1.5 watt keep them?
Client doesn't want MX, so that means no batteries.
You'll need a genny as back up anyway for long power outages during
</pre>
</blockquote>
<pre wrap="">storms, so
get a natural gas/propane unit as back up instead of batteries.
</pre>
<blockquote type="cite">
<pre wrap="">
OK you asked,
jay
peltz power
On Nov 17, 2011, at 4:03 PM, Richard L Ratico wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi Wrenches,
This is a repost. No replies the first time, so I'm trying one last time.
I may be "adopting" an eleven year old, Y2K, grid tie with battery
</pre>
</blockquote>
</blockquote>
<pre wrap="">back-up
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">system. It consists of 12 - Astro-Power 120 modules, installed in 2000,
</pre>
</blockquote>
</blockquote>
<pre wrap="">12 -
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">Evergreen EC-110 modules installed in 2004, only one MX60, which
</pre>
</blockquote>
</blockquote>
<pre wrap="">controls
BOTH
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">sub-arrays, one SW4048 in SELL mode through a dedicated load sub-panel.
Existing, seven year old battery is shot (8-Trojan L-16). Initial bank of
unknown batteries was replaced after only four years.
Recent long, nearby, utility outages have the client requesting a
</pre>
</blockquote>
</blockquote>
<pre wrap="">proposal to
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">include a new back-up generator and to restore the system selling to the
</pre>
</blockquote>
</blockquote>
<pre wrap="">grid.
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">Client may decide go straight grid tie to eliminate the batteries. They
</pre>
</blockquote>
</blockquote>
<pre wrap="">have
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">found the maintenance to be a hassle.
My thoughts so far:
1)To take advantage of most of the existing hardware, I wonder if it
</pre>
</blockquote>
</blockquote>
<pre wrap="">makes
sense
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">to try to improve the system efficiency by relegating the SW to a manual
</pre>
</blockquote>
</blockquote>
<pre wrap="">back-up
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">mode only, where, say, by means of a timer controlling grid availability
</pre>
</blockquote>
</blockquote>
<pre wrap="">through
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">AC1, it would only charge a smaller battery bank once a week. The battery
</pre>
</blockquote>
</blockquote>
<pre wrap="">bank
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">would be small,
a single string of either, sealed gel units or T-105s with the new Trojan
watering system.
2) Provide new grid-tie inverter/s (appropriate string type or Enphase
</pre>
</blockquote>
</blockquote>
<pre wrap="">190s)
to
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">handle the net metering.
3) Provide a way to AC couple the new inverter/s to the SW in the event
</pre>
</blockquote>
</blockquote>
<pre wrap="">of an
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">outage.
4) Provide a new Honda 3000 inverter type generator connected to AC2 in
</pre>
</blockquote>
</blockquote>
<pre wrap="">the
SW.
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">5)Provide a way to lockout the grid tie inverter/s when the generator is
operating.
Any thoughts or suggestions would be greatly appreciated.
Thanks in advance,
Dick Ratico
Solarwind Electric
Bradford, VT
</pre>
</blockquote>
</blockquote>
<pre wrap="">--- end of quote ---
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