[RE-wrenches] Specific AC Coupling question

[Mac Lewis]

Hi Allen,

I would recommend a contactor to disconnect to Fronius at high SOC (or
voltage).  It's pretty inexpensive to do it and most of the battery based
manufacturers recommend it.

I may be misunderstanding Jay, but I believe that the frequency shift in
this case would create an on/off type of charging, meant only to kick the
Fronius off-line.  I wouldn't worry much about that because the FM60 can
perform the Absorb and float parts of the charge cycle.  You may consider
putting in a Conext battery monitor and using that to trigger a relay at
high SOC (rather than voltage) and isolate the Fronius as failsafe.  To me,
that is preferable over the relying solely on the frequency shift.

I am definitely cautious about AC coupling different manufacturers so
please keep us in the loop as to how it works out and if you learn
anything.  It's an interesting grey area, because accountability really
does rest on the installer even if the manufactures suggest it will/should
work.  What do you do if it doesn't?    Perhaps there is a specification
that would clarify if AC coupling would work.  I read somewhere that
grid-tied inverters that test grid impedance will find that  the battery
based inverters have an impedance out of the expected grid specification
and therefore won't AC couple with them, but would like more solid info on
that.

Good Luck

On Mon, Apr 4, 2016 at 6:45 PM, jay <jay.peltz at gmail.com> wrote:

> HI Allan,
>
> The only reason to frequency shift is for “softer” charging.
> VRLA are not as sensitive to the pulse type charging that a relay type
> charging would do.
> And regardless if you have frequency shift or not, you will still need (
> especially with VRLA) a high voltage relay.
> I recommend a SS relay, but a regular mechanical contactor will do as well.
>
> jay
>
> Peltz Power.
>
>
>
> On Apr 4, 2016, at 12:34 PM, Allan Sindelar <allan at sindelarsolar.com>
> wrote:
>
> 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?
>
> 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.
>
> 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.
>
> 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
> --
> *Allan Sindelar*
> <allan at sindelarsolar.com>allan at sindelarsolar.com
> NABCEP Certified PV Installation Professional
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Founder (Retired), Positive Energy, Inc.
> *505 780-2738 <505%20780-2738> cell*
>
>
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-- 



Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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