[RE-wrenches] Convert Grid Tie SW4048 to Backup System; Add New Inverter, AC Coupled

Joel Davidson joel.davidson at sbcglobal.net
Sun Nov 20 09:21:12 PST 2011


Where in the NEC is the requirement for the GTI interface?

----- Original Message ----- 
From: "Kirk Herander" <kirk at vtsolar.com>
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Sent: Sunday, November 20, 2011 3:33 AM
Subject: Re: [RE-wrenches] Convert Grid Tie SW4048 to Backup System;Add New 
Inverter, AC Coupled


> 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: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Richard L
> Ratico
> Sent: Friday, November 18, 2011 6:53 PM
> To: re-wrenches at lists.re-wrenches.org
> 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:
>> 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
> as
> back up.
>>
>> Told you, you wouldn't like it.
>>
>> The SW parts are basically gone and it was a terrible  grid tied inverter
> anyway.
>> 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
> storms, so
> get a natural gas/propane unit as back up instead of batteries.
>>
>> OK you asked,
>>
>> jay
>>
>> peltz power
>> On Nov 17, 2011, at 4:03 PM, Richard L Ratico wrote:
>>
>>> 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
> back-up
>>> system. It consists of 12 - Astro-Power 120 modules, installed in 2000,
> 12 -
>>> Evergreen  EC-110 modules installed in 2004, only one MX60, which
> controls
> BOTH
>>> 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
> proposal to
>>> include a new back-up generator and to restore the system selling to the
> grid.
>>> Client may decide go straight grid tie to eliminate the batteries. They
> have
>>> 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
> makes
> sense
>>> to try to improve the system efficiency by relegating the SW to a manual
> back-up
>>> mode only, where, say, by means of a timer controlling grid availability
> through
>>> AC1, it would only charge a smaller battery bank once a week. The 
>>> battery
> bank
>>> 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
> 190s)
> to
>>> handle the net metering.
>>> 3) Provide a way to AC couple the new inverter/s to the SW in the event
> of an
>>> outage.
>>> 4) Provide a new Honda 3000 inverter type generator connected to AC2 in
> the
> SW.
>>> 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
> --- end of quote ---
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