Balancing Two SW Inverters on the head of a pin [RE-wrenches]

[Bill Brooks]

William, Marco, and Jeff C.,

Here is the method I found to be most effective:

INVERTER SETUP (MENU 9)
set to SELL

BATTERY CHARGING (MENU 10)
set ABSORPTION TIME to 0:00 on both machines.
set MAX CHARGE AMPS to 1 amp on both machines.

BATTERY SELLING (MENU 17)
set MAX SELL AMPS to X amps on both machines. (where 2X is the Max AC amps
that the PV array can produce. (e.g. 4000 Watts should set both to 18
amps --18A*120V=2160Watts)

Both temp comp probes must be installed so as to operate at the same
temperature. I have tried adjusting the float setting and that also works
particularly for an inverter that is out of DC calibration. They still get
out of wack at times at different temperatures because the slope of the temp
comp probes are usually not the same. This should keep both machines selling
as evenly as they can and limit each machine to a maximum of half the AC
Watts output. The one amp MAX charge amps keeps one unit from charging while
the other one sells.

Try it and see how you like it.

Bill.


-----Original Message-----
From: William Miller [mailto:wrmiller at slonet.org]
Sent: Wednesday, September 26, 2001 6:19 PM
To: RE-wrenches at topica.com
Subject: RE: system output honesty [RE-wrenches]


Marco:

I must not have been very clear, but you don't necessarily end up with the
same numeric float voltage setting.  Take the inverter with the lower
output and increase it's float voltage one increment at a time (I think it
adjusts in 0.2 volt increments)  while checking sell amps.  The change
should be immediate and obvious.  (If it doesn't improve, try decreasing
float voltage because my memory may not be accurate.)

William



At 01:09 AM 9/26/01 -1000, you wrote:
>William,
>
>Maybe you have the magic touch with your dual SWs, but my dual SWs are set
>at the same float voltage and, as Bill B. noted, they don't "share" those
>incoming PV electrons very equitably.
>
>On another note, has anyone received an AEI MM5 or MM3 yet?
>
>marco
>ProVision Technologies
>Hilo, land of declining tourism Hawai'i
>
>Friends:
>With dual SW inverters (I believe, if memory serves me right) I finally
>discovered that adjusting the float voltage until they both sell more or
>less equally does the job of balancing.
>William
>
>
>
>
>
>
>At 05:04 PM 9/25/01 -0700, you wrote:
>>Jeff C.,
>>
>>It is less important with a small array, but it still will work slightly
>>better. The much bigger issue with dual inverters in sell mode is that
they
>
>>don't behave nicely with each other (they don't know how to share). One
>>inverter invariably wins the conversion battle and the other inverter sits
>>idle, or more likely, starts drawing power from the grid to fight the
other
>
>>inverter.
>>
>>I have yet to see a dual SW system on the grid the worked really well. You
>>can trick them into working with various settings. I have a set of
settings
>
>>that has worked well for me, others on the list may have their own
methods.
>
>>If people are interested, we can do this onlist. If not, email me and I'll
>>send them offlist.
>>
>>Bill.
>>
>>


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email: wrmiller at slonet.org
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