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

Ray Walters ray at solarray.com
Mon Dec 15 08:03:21 PST 2014


What you want is already programmed into the inverter.  It's called Low 
Battery Transfer mode (LBX), its just a program setting on the 
inverter.  You select this mode in Menu 9, and then its actual battery 
voltage settings are in Menu 16.
It will not sell back in this mode, but fromHome Power Magazine's 
Guerrilla Solar movement of the 90s, all you have to do to sell back: 
"Don't ask, Don't Tell, just press Sell".

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 12/15/2014 8:09 AM, Daniel Young wrote:
>
> 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 Professional^TM : Cert #031508-90
>
> NABCEP Certified Solar Heating Installer^TM : 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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