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

Ken Schaal Ken at commonwealthsolar.com
Mon Dec 15 08:42:53 PST 2014


Ah the good ol' days----
A note from experience..... If the meter reader/ smart meter? sees backfeed, the utility is likely to ask questions. In my customers case, the Co-op was so eager to prove to the Va. SCC that they were on top of net metering ( this was the early days of net meter )--or maybe they just wanted experience with it, they actually sent the Coop engineer and a lineman to the job to test shut off with the grid off. This was with a Trace 6048 Power Panel., vintage 1999. The lineman even put on gloves and face shield before we removed the covers so he could verify no juice to the grid when we turned off the main breaker. Of course nothing happened , except the house power stayed on, as the Trace equipment was designed to sell back, but did not meet the new UL 1741 anti-islanding standard.
The engineer and the lineman were duly impressed~!
And the engineer approved the system for net meter ~!!

One more thing-- check that the utility meter installed records the sell correctly--that is, doesn't count the backfeed as consumption. Around here the new meters -- with remote reading capability--don't differentiate as to direction--unless you sign up for net meter in which case you get the proper meter.

We updated several Y2K systems to new UL certified inverters when the flooded batteries had seen better days.
Sure don't miss all that watering/ equalizing/ and acid mist.
Just a few AGM's now--and an enlarged array.
Anyone need a 6048 Power Panel ?? off list please

Ken Schaal
CommonWealth Solar
Ashland, Va. 23005
804-216-5371

  ----- Original Message ----- 
  From: Ray Walters 
  To: RE-wrenches 
  Sent: Monday, December 15, 2014 11:03 AM
  Subject: Re: [RE-wrenches] RE;SW4024's were off grid, now on grid AC2 Controls?


  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
303 505-8760On 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 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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