[RE-wrenches] RE-wrenches Digest, Vol 2, Issue 818

Drake Chamberlin drake.chamberlin at redwoodalliance.org
Tue Aug 4 05:50:24 PDT 2009


Nick,

Where did you put the relay?  I had problems breaking the AC out of 
Sunny Boy inverters.

Thanks,

Drake


At 07:58 PM 8/3/2009, you wrote:
>Aloha Solar Bozos:
>     I haven't posted here in ages, and I hope I am cutting out the 
> appropriate stuff?  Probably not, but I will give it a try.  I want 
> to reply to Topic 3 regarding backfeeding an off-grid inverter with 
> a grid-tied inverter.
>     In 2004, I back-fed a SWR-2500U into an Outback FX inverter's 
> back-up power panel.  It required a transformer to step down to 
> 120VAC and a voltage controlled relay to shut the Sunny Boy off 
> when the batteries were charged.  Greg at OB said that the 
> inverters would regulate the AC output voltage at ~120V, so when 
> the voltage would rise up from the Sunny Boy's production, the FX 
> was forced to take the power in, resulting in the batteries being 
> charged.  You probably realize that the Sunny Island controls the 
> grid-tied inverter's output but fluctuating the Hertz, which 
> eliminated that issue for them.
>
>From: "re-wrenches-request at lists.re-wrenches.org" 
><re-wrenches-request at lists.re-wrenches.org>
>To: re-wrenches at lists.re-wrenches.org
>Sent: Monday, August 3, 2009 6:47:22 AM
>Subject: RE-wrenches Digest, Vol 2, Issue 818
>
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>Today's Topics:
>
>   1. Re: AC Backfeed Battery Over-Charging (Jeff Yago)
>   2. Broken Modules (Doug Wells)
>   3. Re: AC Backfeed Battery Over-Charging (Tump)
>   4. Re: Broken Modules (Jeff Yago)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Mon, 3 Aug 2009 06:21:56 -0700
>From: "Jeff Yago" <<mailto:jryago at netscape.com>jryago at netscape.com>
>Subject: Re: [RE-wrenches] AC Backfeed Battery Over-Charging
>To: RE-wrenches 
><<mailto:re-wrenches at lists.re-wrenches.org>re-wrenches at lists.re-wrenches.org>
>Message-ID: 
><<mailto:20090803062156.CD9B16AE at resin17.mta.everyone.net>20090803062156.CD9B16AE at resin17.mta.everyone.net>
>Content-Type: text/plain; charset="us-ascii"
>
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>
>------------------------------
>
>Message: 2
>Date: Mon, 3 Aug 2009 09:32:08 -0400
>From: Doug Wells 
><<mailto:dwells at thesolarspecialists.com>dwells at thesolarspecialists.com>
>Subject: [RE-wrenches] Broken Modules
>To: 
><mailto:RE-wrenches at lists.re-wrenches.org>RE-wrenches at lists.re-wrenches.org
>Message-ID:
> 
><<mailto:D6573665-38CE-4E54-A70F-F7AC8F630DF3 at thesolarspecialists.com>D6573665-38CE-4E54-A70F-F7AC8F630DF3 at thesolarspecialists.com>
>Content-Type: text/plain; charset=US-ASCII; format=flowed
>
>Wrenches,
>
>I am curious what other installers are doing with broken modules?
>I know some manufacturers are starting recycling programs.
>
>
>Doug Wells
>The Solar Specialists
>Morrisville, VT 05661
>(p) 802-223-7014
>(c) 802-498-5856
><http://www.thesolarspecialists.com>www.thesolarspecialists.com
>
>
>
>
>
>
>
>------------------------------
>
>Message: 3
>Date: Mon, 3 Aug 2009 09:39:21 -0400
>From: "Tump" <<mailto:tump at hughes.net>tump at hughes.net>
>Subject: Re: [RE-wrenches] AC Backfeed Battery Over-Charging
>To: <<mailto:jryago at netscape.com>jryago at netscape.com>, "'RE-wrenches'"
> 
><<mailto:re-wrenches at lists.re-wrenches.org>re-wrenches at lists.re-wrenches.org>
>Message-ID: <CAFB0B2FF97B4386BB4EF00DF46766F9 at tumpdggfbh2yn6>
>Content-Type: text/plain; charset="us-ascii"
>
>Hey Jeff this was something that Greg @ OB was working on summer of 06.....
>Should have it tump, almost got it little problem .... Ahhh sorry we are no
>longer working on that! I was in the middle of a large AC Coupled system &
>had been waiting for 4 months for this "trick" soft ware to come on line.
>Perhaps CF might be able to update us on this software. Kinda of a no
>brainier perhaps, John B & the boys @ SMA patented this "trick" software.
>
>
>     <mailto:Tump at swnl.net> 
> <mailto:Tump at swnl.net>Tump at swnl.net        <http://www.swnl.net/>
><http://www.SWNL.net>www.SWNL.net
>           Solarwinds Northernlights
>   Serving Mid Coast Maine & Northern California
>     Me.# 207-832-7574  Cl.#  610-517-8401
>
>                           Blair "TUMP" May
>       ********  MAINE'S CHARTER ********
>             NABCEP    "Certified PV Installer"
>
>       ********  MAINE'S CHARTER ********
>   Trace Xantrex "Certified" Dealer / Installer"
>
>
>
>-----Original Message-----
>From: 
><mailto:re-wrenches-bounces at lists.re-wrenches.org>re-wrenches-bounces at lists.re-wrenches.org
>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jeff Yago
>Sent: Monday, August 03, 2009 9:22 AM
>To: RE-wrenches
>Subject: Re: [RE-wrenches] AC Backfeed Battery Over-Charging
>
>
>I have a question that may be one of those that everyone wants to know the
>answer but feel they are the only one that doesn't know the answer, or
>perhaps I am the only one that doesn't know!.
>
>In an AC-coupled system, i.e. the 240 VAC output solar inverter mounted at a
>distant array (240 VAC out to reduce long line loss) is wired to the 120/240
>VAC output emergency panel supplied from a battery based inverter.  This
>allows the solar inverter to stay up when the grid goes down since it thinks
>the grid is still up on the load side of the battery based inverter.  The
>battery based inverter will use any excess backfed power from the solar
>inverter that is in excess of the other supplied loads to re-charge the
>battery.  However, when this happens the battery charging process can boil
>the batteries when there are no other loads running.
>
>I have been told this is because the battery based inverter does not
>regulate its charging of the battery when using backfed power from its
>output panel, but I still don't understand why.  If the battery charger in
>the inverter can provide regulated 3-stage battery charging when the power
>is supplied from the grid or a generator, why does it suddenly become a full
>output un-regulated battery charger when power is supplied from backfeed and
>will keep charging regardless of reaching a high battery voltage?
>
>I would have assumed the battery charger section would charge the same way
>regardless of where the power is being supplied from, or perhaps just
>shutdown on some kind of backfeed safety.  As far as I know, this
>over-charging problem in an AC coupled dual inverter system is true for all
>battery-based inverters.  Any inverter techs out there that can explain
>why?  Perhaps this would be a nice feature in future high-end battery-based
>inverters so we no longer need the custom power relay field wiring to
>provide this high voltage cut-out?.
>
>Thanks,
>
>Jeff Yago
>
>
>
>   _____
>
>Netscape.  Just the Net You Need.
>
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>------------------------------
>
>Message: 4
>Date: Mon, 3 Aug 2009 06:47:21 -0700
>From: "Jeff Yago" <<mailto:jryago at netscape.com>jryago at netscape.com>
>Subject: Re: [RE-wrenches] Broken Modules
>To: RE-wrenches 
><<mailto:re-wrenches at lists.re-wrenches.org>re-wrenches at lists.re-wrenches.org>
>Message-ID: 
><<mailto:20090803064721.CD9B1303 at resin17.mta.everyone.net>20090803064721.CD9B1303 at resin17.mta.everyone.net>
>Content-Type: text/plain; charset="UTF-8"
>
>We have only had one broken module due to shipping damage and this 
>was the bottom 200 watt module in a shipment where each 2 modules on 
>the pallet were in heavy cardboard shipping boxes.  Of course this 
>not discovered for several weeks until we worked our way down the 
>stack.  However, since suppliers like Evergreen have switched to the 
>plasic corners that allow stacking modules without any cardboard 
>packaging, we have had no more breakage in shipment.  I assume the 
>fork truck drivers now see a large stack of glass and take a little 
>more care whenre thay ram the forks.
>
>As far as what we did with our broken module (which taught a very 
>expensive lesson about checking shipments), we keep it to show 
>students in our training classes what happens when things go wrong.
>
>Jeff Yago
>
>_____________________________________________________________
>Netscape.  Just the Net You Need.
>
>
>------------------------------
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>End of RE-wrenches Digest, Vol 2, Issue 818
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648  
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