The frequency shift will only taper charge using
all SMA equipment and an RS-485 Data Module and
data cables. With all other brands of grid tie
inverters, the Sunny Island will trigger and on / off charge scenario.
At 12:09 AM 4/5/2016, you wrote:
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? Â Â 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
<<mailto:[email protected]>[email protected]> wrote:
HI Allan,
The only reason to frequency shift is for âsofterâ charging.
VRLA are not as sensitive to the pulse type
charging that a relay type charging would do. Â
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
<<mailto:[email protected]>[email protected]> 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
--Â
Allan Sindelar
<mailto:[email protected]>[email protected]
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder (Retired), Positive Energy, Inc.
<tel:505%20780-2738>505 780-2738 cell
Â
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