[RE-wrenches] Specific AC Coupling question

[Drake]

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:jay.peltz at gmail.com>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. 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:allan at sindelarsolar.com>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
>>--Â
>>Allan Sindelar
>><mailto: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.
>><tel:505%20780-2738>505 780-2738 cell
>>
>>Â
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