[RE-wrenches] Specific AC Coupling question

[drake.chamberlin at redwoodalliance.org]

Hi Allen

I haven't tried this with Schneider, but we do have one system that
frequency shifts a Fronius IG Plus 10.0 from a pair of Sunny Islands.
Maybe a different degree of shifting is present. SMA tech support felt
confident.


Drake

>     Wrenches,
>     Core question first: Will a ~2010 Fronius IG-4000 respond properly
>     to the frequency shift regulation supplied by a new Schneider
>     XW+5548 or XW+6848?
>     <br>
>     Situation: I haven't seen the Colorado site; I'm working as a
>     consultant to produce an upgrade component list and will later serve
>     as a resource during local installation of the upgrade equipment.
>     Customer has hired me to turn a hodgepodge system into a GTBB
>     system. The system has two key parts: an existing SW5548 with
>     batteries, never properly installed (only AC1 in was ever connected
>     to a main load center!) with 3.1 kW of tracker-mounted PV through an
>     Outback FM60; and a roof-mounted 4kW array feeding the grid panel
>     via the IG-4000. As currently installed, nothing will operate as
>     wired during a grid outage, and a 240V AC well pump isn't
> supported.<br>
>     <br>
>     The simple plan is to replace the SW5548 with an XW+5548 or 6848
>     with Midnite E-Panel; replace batteries with Surrette FLAs; keep
>     existing arrays unchanged; use existing FM60 for smaller tracked
>     array; use existing Fronius IG-4000 but AC couple it to the output
>     of the XW. The customer understands that sell amperage is limited by
>     the inverter (to 20A @ 240V for the 5548, or 4,800W, or 27A @ 240V
>     for the 6848, or 6,480W) when the grid is up, but the full array can
>     charge the battery bank when the grid is down.<br>
>     <br>
>     Schneider tech support assures me that the XW+ is good in this
>     application, but I need to get an OK from Fronius about
>     frequency-shift compatibility. Fronius tech support tells me that it
>     may or may not work: the 0.4 hz shift is within the the normal
>     frequency tolerance for this model. While the tolerance window may
>     be tightened up in the field, such tightening may cause nuisance
>     tripping, especially with reactive loads like a well pump or A/C.
>     The tech suggested that we first test the frequency-shift approach,
>     and add a DC-coil contactor between the output of the Fronius and
>     the XW+ if it doesn't.

>     Has anyone AC coupled these two units? Did it work? Any unexpected
>     problems? Did you add a voltage-controlled contactor? What should I
>     advise my client?
>     Thank you,
>     Allan
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