[RE-wrenches] Max AC coupling backfeed?

Tue Sep 16 16:33:46 PDT 2014

Hi:

When we developed the AC coupling capability of the XW's we of course 
looked at what happens when the AC coupled power is larger than the XW 
power.

As William points out as long as the loads are larger than what the AC 
coupled inverter can supply, then there is no problem.  However, this only 
works if the loads are consistently larger.   A load such as a pump or 
heater will not meet this requirement if it switches off as it cycles in 
normal operation.

If a large load falls off during AC coupling, then whatever power is being 
produced by the AC coupled inverter above any used by remaining AC loads 
will within one AC cycle show up as a charging current to the battery. 
Depending on the particulars, this abrupt and immediate increase in 
charging current can cause an overload shutdown of the inverter/charger.

For this reason we do not support AC coupling in systems which have a grid 
tie inverter with a power output larger than the inverter charger.

Having said that, engineering is currently working on improvements to AC 
coupled charging operation, so the situation may change.

JARMO
_____________________________________________________________________________________ 

Jarmo Venalainen  |   Schneider Electric   |  Solar Business  |   CANADA | 
  Training & Development Specialist - Senior 
Phone: +604-422-2528  |   Fax: +604-420-1591  |   Mobile: +604-505-0291 
Email: jarmo.venalainen at schneider-electric.com  |   Site: www.SEsolar.com 
|   Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 

*** Please consider the environment before printing this e-mail 

From:
William Korthof <wkorthof at gmail.com>
To:
RE-wrenches <re-wrenches at lists.re-wrenches.org>, 
Date:
09/14/2014 09:17 AM
Subject:
Re: [RE-wrenches] Max AC coupling backfeed?
Sent by:
"RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>

I've successfully operated isolated temporary installations where the 
ac-coupled inverter output significantly exceeds the battery-backup 
inverter nameplate rating. Obviously there has to be enough "firm" AC load 
to absorb at least the portion of the AC coupled output that exceeds the 
grid tie inverter capacity. 

Hypothetical example: 
(3) Power One 6 kW 240 output grid-tie inverters with 7.5 kW of PV modules 
each. 
(2) Schneider XW6048 battery backup inverters

Suppose the supported AC load consisted of a mix of refrigeration and 
other heavy loads with minimum demand during sunny hours of 6 kW. 
Or suppose the solar array consisted of modules on steep 45 degree 
East/West roof surfaces...

/wk

On Sep 14, 2014, at 8:55 AM, Tump <tump at swnl.net> wrote:

All, I am wondering what the max AC Coupled back feed into an OBGTVX 3648 
might be. I have installed a 4.9 STC array into a SMA TL5k inverter and 
the customer presently has an single OB GTVX with a T240 into a Eback up 
load panel. I would like to know if there are any limitations in this type 
of configuration using an AC coupling situation to operate during a grid 
failure.
Thoughts please.

Tump at swnl.net               www.SWNL.net
                Solarwinds Northernlights    
       Serving Mid Coast Maine & Northern California
                         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"

_______________________________________________
List sponsored by Redwood Alliance

List Address: RE-wrenches at lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
______________________________________________________________________
_______________________________________________
List sponsored by Redwood Alliance

List Address: RE-wrenches at lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20140916/069fbe65/attachment-0003.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 14092 bytes
Desc: not available
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20140916/069fbe65/attachment-0002.jpe>