SW again [RE-wrenches]

[Kurt Nelson, SunWise]

Hey Sharkey,

When I said "I don't think we should have to sell two inverters", I was
referring to the  suggestion Travis  made of using an ST to sell to the
grid and a PS or DR to power the homes loads.  

I have a number of SW4024 grid-tied systems with battery back up.  Most
have a battery capacity of 700AH.  The system I have installed extra
metering on and am first going to modify has such a battery and fairly
modest loads on the sub-panel dedicated to the Trace.  My thought it to
simply disconnect AC1 with the Grid-usage timer sometime shortly after
usable sun hour.  Grid usage would be programmed to come on the next
day, perhaps early to mid-morning.  A contactor placed in line of AC1
would have fallen out over night, as it is controlled by the N.O.
contact of an Aux relay set to close at the Traces Bulk Voltage setting
and the Hysteresis set to something below float voltage.  Shouldn't this
work as is?  

Problem?  If she (owner) uses more energy than anticipated and gets into
cloudy weather, how does the Grid come back into play when it is really
needed.  Could this be another Aux relay set very low and utilizing the
N.C. contacts to pull in the same contactor at a lower battery voltage? 
Using the NC contact, it would close when the relay's Hysteresis setting
was met, making it perhaps 23VDC?  The upper end of this Aux would be
the Trace's bulk voltage setting again, right???

Question?  I have never utilized the grid-usage timer function.  It does
when it sounds like it does?  When grid usage is re-established, does
the inverter try and initiate a charge cycle (as it does when AC1 is
lost for a period), or being that AC1 hadn't actually been lost to the
inverter, does it not get into the charge cycle deal??

Kurt Nelson

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