[RE-wrenches] Max AC coupling backfeed?

[William Korthof]

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.

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