[RE-wrenches] AC Coupled Issues

[Dave Click]

Jeff- The Sunny Boys can be reprogrammed into "off grid" mode so they 
can work between 56-64 Hz, but I believe you need both a service cable 
and a call to SMA tech support to make that happen. They then note in 
their system that that inverter's been adjusted to no longer meet UL 1741.

Jeff Yago wrote:
> As mentioned before, many of our clients want battery backup with
> their solar, but are not off-grid.  They also want a generator so
> battery banks can be down-sized.   For many of these applications we
> use a SunnyBoy at the array when the aray is located hundreds of feet
> from house, and usually a Xantrex battery based inverter at the
> house, and backfeed the solar inverter into the inverter's emergency
> loads panel.  We pass this backfeed through a heavy duty relay
> controlled to open on high battery voltage. Yes, SunnyBoy with
> SunnyIsland is better match, but since one is 120 V and the other is
> 240V that means adding transformers or using two SunnyIslands.
>
> Here is the issue - The SunnyBoy is working perfectly when grid power
> is passing back to it through the backfeed connection.  However, when
> this system operating off-grid when the grid is lost, the SunnyBoy
> "sees" the fake grid power coming from the Xantrex which it shows on
> L1 and L2 readings, but it is staying in the waiting mode and will
> not connect.  No errors, just acts like grid a morning startup and
> stays that way.   I have had problems before with Fronius doing this
> and they have provided secret codes to open up the program settings
> for the grid which solves the problem when grid power is poor quality
> typical at end of line.  Is this solution possible with SunnyBoy
> inverters, or is there something else going on.  Have not had this
> problem on other AC coupled systems using the same combination of
> inverters.
>
> Thanks,
>
> Jeff Yago
>
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