[RE-wrenches] RE; SW4024's were off grid, now on grid AC2 Controls?

[Daniel Young]

The way I would do this if using outback (really what I'm familiar with) is
to set up the aux relay on the inverter to trigger an AC relay that
connected the grid to the inverters ac input using the "load shed" function.
It would trigger the relay when the batteries reached a set voltage (user
programmable in the outback), then disconnect the grid at higher set
voltage. Ex: activate relay at 46V, then de-activate relay at 50V (48V
system). All you are basically doing is activating a charging source instead
of severing a load to help the battery state of charge. Not sure how the
trace handles AC1 and AC2, so maybe you'd need a second relay to make sure
the generator input is always off when the grid input is active.

 

Not sure if the trace has this functionality. Hope this applies, or helps
get you down the right path.

 

With Regards,

 

Daniel Young, 

NABCEP Certified PV Installation ProfessionalTM: Cert #031508-90

NABCEP Certified Solar Heating InstallerTM: Cert #SH031409-13

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
Behalf Of Dave
Sent: Sunday, December 14, 2014 8:10 PM
To: 'RE-wrenches'
Subject: [RE-wrenches] RE; SW4024's were off grid, now on grid AC2 Controls?

 

Here is a request for advice from one of my old off grid customers who has
recently brought in the grid to lessen his dependence on the generator. He
is NOT selling back to the grid.

 

The main question I have is this: Can we program the Trace SW4024 so that
that it will charge the batteries with Grid Power (AC2) when a low voltage
setting is reached?

 

<< "I have two SW4024 inverters.  They are set up to each handle about 1/2
of the loads in the house.

 

Our system is setup so we are either on Grid power, or battery power.  

The choice is controlled by a manual transfer switch.

 

AC1 on both inverters is backup generator which is controlled by Inverter #1
when battery voltage reaches preset levels.

 

AC2 on both inverters is AC from the grid and is currently controlled by
circuit breakers.  The circuit breakers are normally in the off position and
the batteries are charged by the sun.  Typically if we want to charge the
batteries a bit with grid power we turn on the circuit breakers and the
batteries are charged through both inverters by utility power.

 

What I would like to be able to do is set the inverter, probably inverter #1
for consistency, to allow grid charging at a set battery voltage and then
cut off the grid when it reaches an upper voltage.  My thought is something
along the lines of, if the batteries reach 40% of full charge Grid is
started and allowed to charge batteries until they reach 80% charge.

 

I would like to continue as things are at present with the inverter
triggering the back-up generator if needed.  Again my thought is at 35% of
Full charge Generator is started and is then shut off at 80% of full charge.

 

My goal is to use PV juice as much as possible with first backup being Grid
and second backup being Generator.  This should allow us to go away and
hopefully run the house on PV but have two backups if needed". >>

 

 

I would appreciate advice from anyone with experience with a system like
this.

Best,

Dave

 

David Palumbo 

Independent Power LLC

462 Solar Way Drive

Hyde Park, VT 05655

802-888-7194

 

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