Balancing the Loads of my Conext SW with an Autotransformer

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Comments

  • mcgivormcgivor Solar Expert Posts: 2,401 ✭✭✭✭✭
    Good to hear, questions are always welcome, just trying to offer other solutions.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    900W  3 × 300W No name brand Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal as a backup system. 
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergencies and welding.
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited August 16 #33
    mcgivor said:
    Good to hear, questions are always welcome, just trying to offer other solutions.
    Thanks.  And I do appreciate it.  I had seriously considered the other option,  but when the parts offer fell thru, and I found the PSX for 1/2 price seemed like a good idea at the time.    It also seems easy enough to wire up.   So I am hoping this will be a good fix for the SW inverter and it's AC Support Mode in North America.  (obviously, markets where 120v service is not use,  load balancing is not a problem for the SW)
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    Someone just responded this to me on the Outback Power forum.    It might be that he is correct ...

    I don't know the SW topology but from your description, it sounds like the SW has an internal transformer creating the split 120/240 output. If this is the case I don't think you will have much luck balancing the load with an auto-former (PSX-240 etc). Your best bet would be to balance the loads/circuits in your AC panel if possible. It works for the OB FX inverters because they are two isolated power supplies that are set up to work as a 2 wire 240V circuit. The auto-former is the only point of inductance between the two.

    But if this is true,  why would the PSX work to balance  the power coming off a generator?   The PSX is also used in that application.  (pardon my ignorance,  this is an honest question,  not a challenge.)
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mcgivormcgivor Solar Expert Posts: 2,401 ✭✭✭✭✭
    In the Outback example, both neutrals are common, so in essence it's the same as the SW, wether the source is two inverters or a transformer providing a split phase, as long as there are two live and a single neutral what would change?  This is logical thinking of course, sometimes things need to sink in to come up with a rationale why it would or wouldn't work, but on the surface it would appear the same.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    900W  3 × 300W No name brand Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal as a backup system. 
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergencies and welding.
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭

    do you have any idea if what I am doing will work with the SW inverter and the PSX-240 Auto transformer?  the post I posted at #34 here above starts to throw the idea into question.  

    But several months ago Schneider Tech told me yes it would work,   and yesterday Outback Tech told me it "should work but they had not tested it with the SW"

    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited August 23 #37
    Well the "deal" I found on the PSX-240 arrives tomorrow.  I originally was going to try an FW-X240, but decided I would be better off with the included box and breakers of the PSX-240 rather than trying to enclose the raw FW-X240 on my own.

    I do have some questions about wiring (and I will show my ignorance here).   Originally I had been looking at the manual and wiring for the FW-X240 raw transformer which seemed pretty straight forward.   This is from the manual for the FW-X240 for installing as a  Load balancing transformer


    This is the method I was planning on using.  It is not showing the Neutral to Loads ... but I assume this left out for simplicity?   A Neutral would come off the Neutral bus bar and run to each 120v L1 and L2 Load?

    *************************************


    But when I decided to go with the PSX-240,  there is no such wiring diagram in the manual.  Instead  the PSX-240 manual shows this for a Load Balancing set up ...



    Both of the examples above are directly from the OutBack Power Manuals for the FW-X240 and the PS
    x-240, But This wiring for the PSX looks kinda different from the one in the first example for FW-X.  

    Why is a 120 VAC show wire nutted to a Neutral coming off the L2 source?   

    In my desire to balance the loads can I just use the wiring diagram in the first example and wire the PSX-240 like the FW-X240?

    Does anyone know,  is the transformer in the PSX-240 electrical box  the same as the bare FW-X240??   

    Do I keep my system neutral where it is, connected to my neutral bus bar and simply connect the 2 neutrals of the auto transformer to the same bus bar? 

    Thanks
    Mike
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • EstragonEstragon Registered Users Posts: 3,016 ✭✭✭✭✭
    My understanding is the bare transformer is the same as the one in the box with breakers etc.

    I think the diagram is showing the wire nut to the L2 live. The caption referencing neutral is just showing 120v from L2 to neutral, not saying to connect L2 to neutral. If the second diagram added a wire nut to L1, it would be essentially the same as the first?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited August 23 #39
    Estragon said:
    My understanding is the bare transformer is the same as the one in the box with breakers etc.

    I think the diagram is showing the wire nut to the L2 live. The caption referencing neutral is just showing 120v from L2 to neutral, not saying to connect L2 to neutral. If the second diagram added a wire nut to L1, it would be essentially the same as the first?
    Well I did say above I would be showing my ignorance,  but That's what I thought.  I plan to wire the PSX as shown in the first diagram.   Hopefully I can post some compare-and-contrast shots of the power flow before-after / with-without the PSX with the Schneider Conext SW Inverter. 

    If it works,  it is going to be a game changer for how I use the system.  It will bring me back to my original intent and design.  


    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited August 24 #40
    OK the OutBack Power PSX-240 arrived today.    It was sold as "new" on eBay,  but looked a little worn. It had clearly never been installed,  but there was some misforming of the case (not really dented, just misshaped) and there was corrosion/surface rust on the transformer housing and some of the neutral connections.   Everything else looked good.    My guess is it was stored in a shop or garage in S. FL with no climate control.
    Ok,  so on to the install.  Before I got too committed to it,  (if it doesn't work I can still resell it) I decided to do a temp install.  I used the install diagram that was shown above for load balancing / stacking of 2 Outback power inverters.    But I am using a Schneider Conext SW 4024 split phase inverter.  I believe it has a single transformer inside that yields and L1 and L2 giving the user 240v split phase.    The reason I am installing the Autotransformer is explained in post #1.
    Here is the Temp install

    Here is the Size of the unit



    I simply connected the Red wire winding 1 from the AT breaker to my L2 inverter output bus bar and the Black wire winding 4 from the AT breaker to my L1 inverter output bus bar.  connected the neutral of the AT  windings 2 and 3 to the neutral bus bar of the inverter.     So just 3 wires and a ground going to the inverter switch gear box from the AT box.
    Powered it up with no loads.  Every thing worked.   
    Added loads and here are the results while running AC Support mode and grid connection/support.  Not perfect,  but now AC support mode works almost perfectly with unbalanced 120v loads on the Conext SW Inverter. 

    Here is a 120v 1000w water heater element and my fridge both running on L1  without the PSX-240 AT using the Conext SW in AC Support Mode

    And With the PSX-240 AT


    Here is the fridge and some low voltage stuff.  Fridge is L1 and other stuff is on L1/L2.  Without PSX-240 AT using the Conext SW in AC Support Mode

    With the PSX-240 AT

    Not a lot of difference,  but the load in general is pretty low.  And the SW has to draw at least 2 amps from the grid at all times (when there is a load) so that it does not back feed the grid.

    Here is the Washer on L2 and the Fridge on L1 with the 240v well pump on the PSX-240 AT using the Conext SW in AC Support Mode





    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited August 24 #41
    So the end result is I believe overall positive.  I would say the PSX balances  the various 120v loads  that were unbalance, now drawing from both L1 and L2 of the inverter and allowing the SW's AC support mode to work more or less as advertised.   So in the end,  the PSX Autotransformer seems to make the North American version of the SW invert work more effectively using AC support mode. 
    I am happy with the outcome.


    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited August 24 #42
    mike95490 said:
     But why not wire that heater to 240V and spare a LOT of trouble? That heater is a huge imbalance and I'm surprised the inverter even tolerates it ...

    grainger has several 240V, 750 & 1,000 w elements, and then you could use a fairly smallish (lower losses) transformer,
    by shifting the big 120v loads, to 240V.  Maybe the microwave & blow dryer would need a larger transformer to support them but how many hours do they actually run, and is a $500 transformer worth $20 of electricity ?

    Funny thing @mike95490 ,  when you suggested it back in mid March,  I did just that.  I got the 1000w 240v element and it has been running fine.   UNTIL TODAY.  Oddly,  after I picked up the PSX at the post office,  I came home mowed the grass and with the PSX still in the box discovered I had no hot water ???? What?  I did not know it, but it had been out since yesterday.
    Upon testing I discovered the little element from Granger had already burnt up ??   Wow.  That thing did not last long.  So I installed a 240v 4500w element that I had and connected the water heater back up to 120v (which in theory gives me 1125 watts from the WH element - in practice its more like 1020w). 
    So the pics of testing above with and without the PSX  and the Water Heater are using the 120v water heater element.   And it is working really fine.  Now that i have the PSX-240 AT, I will probably keep the WH at 120v because the 240v 3000-4500w elements are much easier to come by.
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mike95490mike95490 Solar Expert Posts: 8,011 ✭✭✭✭
    I'd send that element back to Grainger, it should have a +10 year lifetime
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    mike95490 said:
    I'd send that element back to Grainger, it should have a +10 year lifetime
    I might,  but it was only $7 and it was almost double for shipping.   So by the time I shipped it back I might not be ahead by much. 
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mike95490mike95490 Solar Expert Posts: 8,011 ✭✭✭✭
    There may be a Grainger store in your area, if so, report the failure and exchange when you go into town.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    What kind of generator are you using?
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    Not using a generator at the moment.  Have a 4000watt one that is being rebuilt
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited August 26 #48
    I have done some more testing with the PSX-240 Autotransformer today.  Using a load on L1 only:
    • L1 load 1120 Watts
    • No Load on L2
    • Without PSX AT the SW drew nothing from the battery, whole load came from Grid
    • With the PSX AT it drew 740W from Battery and 380W from grid
    Ran some other loads with it,  and over all testing different loads and  balanced / unbalanced combinations,  I am getting about 66-70% of the load from battery/solar.  This is up from 0-11% without the PSX AT.
    I then compared the L1 only load with my 240v balanced well pump load by itself at 800W, and with the PSX AT on and the SW set in AC Support mode (same as the test above),  even the balanced load of the 240v well pump ran at about 69% from battery and the rest from grid.
    So I think the PSX-240 is doing what I had hoped it would do.  Perhaps not quite as well,  but still very good.  Especially since the SW inverter will require that the total system draw 2 amps from the grid at all times when loads are present.
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • ewbewb Registered Users Posts: 11 ✭✭
    Interesting discussion & very helpful to me.

    By way of disclosure I do not own a Conext SW or any other battery inverter so my comments are based entirely on my background and my reading (I am a retired EE, but without a career focus on power distribution or power electronics - just a late acquired interest).  I am considering a purchase to create a backup power system, and this entire discussion has given me pause with regard to the Conext SW.


    The key point: AC Support on the Conext SW injects current based on the lowest amount of load on either L1 or L2.  The remaining difference will be supplied by the AC Input source.

    The FAQ says nothing about monitoring/measuring the AC input currents, only the load current.  Makes me wonder if the SW actually does not have a way to measure the AC input current?  It also seems to me that the design priority here is to avoid accidentally feeding power back to the AC input (whether it be a generator or the grid) over making AC support work properly.  This may be necessary given that the SW is not certified to "sell" to the grid.

    Personally I'm more interested in the SW's "load shaving" feature, which is said to operate similarly to AC support.  I'm assuming that the SW will therefore inject current from the inverter but to a lesser degree in an attempt to reduce the load on the AC input rather than eliminate it as it is supposed to do under "AC support."  This assumption may be wrong, but without more information it is the best I can do.  So I also assume that "load shaving" won't work well with an unbalanced load.

    There is much discussion here of "fixing" the load imbalance by converting the water heater to 240v operation.  This would certainly be an improvement, but the fact is that keeping the phase loading in balance in a (US) residence all the time is impossible.  Just flip on the microwave oven or vacuum, or ... and you add 1200 watts of load to one phase.  If you are running with a "small" generator the sudden phase imbalance could overload it since the SW will not draw from the battery to correct the imbalance.

    So, the OP's addition of an external auto-former does seem like the right approach, but a rather expensive one to fix a flaw in this relatively inexpensive inverter.  If one is going to do that, then maybe it would be just as well to use a 120 volt inverter that has good generator support and derive split-phase with the auto-former? Of course if you already own the SW then this seems like the best approach.

    Interesting however that the SW apparently takes its output from a center tapped secondary winding of an internal transformer which acts as an auto-former when power is being fed through from the AC input.  So by adding an external auto-former you are effectively wiring it up in parallel with the one inside the SW.  Indeed, the SW supposedly can accept AC input from a 120 volt supply on L1 and produce 120/240 split phase output, and tolerate at least some load imbalance. See image below from Schneider.

    Finally, I think that to perfectly balance the loads on the SW with an auto-former it may be necessary to leave both neutral terminals of the SW unconnected, turning it into a single-phase 240 volt device. The SW installation manual appears to say that the input and output neutral terminals are electrically common (unfortunately) so you can't get away with just leaving the output neutral unconnected. The reason is that with the neutral connected, some of the phase balancing current will flow within the auto-former that is internal to the SW and this may result in the SW "seeing" an imbalanced load anyway.  That being said, since the PSX-240 is probably a much larger transformer than the one in the SW, with correspondingly heavier windings and thus lower impedance, it is likely to absorb more of (perhaps even most of) the neutral current, and so even with the SW neutral connected it may mostly balance the load and be an effective solution to the problem (as the OP has reported).

    I cannot say however that the SW will operate effectively or even safely with no neutral connection. That connection is the only thing that is keeping the two output voltages nearly balanced at 120 volts each (to neutral).  You are therefore relying entirely on the neutral connection of the external auto-former to balance the voltages on its output.  This should be fine, unless of course there is some reason why the SW doesn't work with a floating neutral. So DON'T TRY THIS based on my comments alone. Your inverter might catch fire and burn or explode for all I know!

    My commentary may seem irrelevant since the OP has reported success, but for anyone thinking of buying an SW and operating it with a small, fuel efficient 120 volt generator and relying on Load Shaving to protect it from overload you might want to think again, or at least factor in the cost of the external auto-transformer.  This cost has me now thinking about a 120 volt Victron or Outback FSX with a step-up auto-former as an alternative solution.  Or. if you want a more powerful (and expensive) solution then a Conext XW+ could be considered with possibly a smaller transformer to step up the 120 volt output of your small generator into the XW+.  Again, I don't have the experience to say if any of these ideas are going to work.





    42 300W Solarworld. SB6.0, SB3.8, SB3.0 Owner installed. Mitsu. Hyperheat, State HPX-80. All electric, net+, climate zone 6.

  • Dave AngeliniDave Angelini Solar Expert Posts: 4,125 ✭✭✭✭
    ewb,  
    In XW inverter (NA) will not have this balance issue with most home loads because it is a large enough inverter/charger.
    The same with a 4kw radian from outback and its 8kw version.
    Think about it, most homes have a 100 to 200 amp service and you are either powering a 30A inverter/charger or a 60A.
    Which one will have issues?
    This is not a new problem because in the old days it was pretty common knowledge. I think it is great that folks have got this too work reasonably but, what a pain. It also looks somewhat unsafe to have all of these components laying there. It should be all in one box, in my opinion. A home insurance inspection would have issues with a complicated home power system. I have seen them fail for insurance.

    If I was not so busy right now before winter I would add this dilemma to the FAQ section in the forum here. It might help someone make the best decision for their situation.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • ewbewb Registered Users Posts: 11 ✭✭
    Dave,

    Thanks for the input.  My apologies if it seems like I am treading well-worn ground here.  I readily admit to a severe lack of real experience, and excessive reliance on my theories. I am simply trying to avoid gaining some very expensive education by buying the wrong product!

    That Schneider FAQ also says this:

    Cause:
    The way the Conext SW unit uses AC Support is very much different from the behavior of Grid Support in the XW and XW+ units.  It will still use excess power on the DC bus to power loads, but they way the power is distributed is much different on the Conext SW. 

    So I don't think the SW is just a mini-XW, but is a different design.  With respect to its advertised "AC Support" and "Load Shaving" functions I think it is a compromised design and not just under-powered. The fact that these features were added in a later firmware release also makes me suspect that the hardware was not originally designed to do these things.

    I will go out on a limb and speculate that the fundamental problem is that it cannot measure and respond to the amount of AC input current, or at least not on both legs separately.  If true, this would prevent the firmware from implementing a feedback loop to inject the right amount of power from the inverter to zero out the input current, as promised for AC Support, or to limit the input current to a specified level as promised for "Load Shaving."  The fact that it is "not allowed" to ever feed power back to the AC input may contribute to this compromise, as may the transformer topology which prevents it from directly supplying different amounts of current onto the two legs.

    In other words, I don't see much hope that Schneider will "fix" this problem with a later firmware release.

    The solution presented by MrM1 does seem viable, if unfortunate and expensive.  I agree that it could veer toward being Rube Goldbergish. That could be avoided with a professional final installation of all the units. As to insurance - that would be a bugger, no doubt. Insurance companies exist to discourage people from taking risks at all. I for one don't want them to dictate my life.  The question might be whether MrM1's solution is less expensive than moving up to an XW+?  Or perhaps whether you are willing to pay for the higher power level and (presumed) better quality of the XW+, even if you don't need a 60 amp solution?

    Oh, and I should say that I know I am ignoring reactive power and the possibility of a reactive power imbalance. I have no idea what the effect of that might be on a low power input source like an inverter/generator except that it certainly wouldn't help.

    And yes I could wait for a nicely integrated solution like the new Outback Skybox, but the lack of technical manuals and answers to questions like whether it does "generator support," and apparent high cost don't bode well at least in the near term.

    I need to go study up on the XW and try to answer my key question: Could it properly do "generator support" for a very small 120 volt only generator stepped up through a 2kVA auto-former?  Or is there a better way to do this? Or a good reason to just not even bother? And in my case to also integrate PV power from my existing grid-tied system (SMA).  I'm now re-considering Outback FXR/VFXR, Victron, XW+, or maybe even the Sunny Island though that is a very different kettle of fish and hardly inexpensive either.
    42 300W Solarworld. SB6.0, SB3.8, SB3.0 Owner installed. Mitsu. Hyperheat, State HPX-80. All electric, net+, climate zone 6.

  • Dave AngeliniDave Angelini Solar Expert Posts: 4,125 ✭✭✭✭
    You get what you pay for. Yes the CSW is dumbed down to meet a price point. They are fine for what they are but I would never depend on one for what you folks are trying to do with the grid. Offgrid they are fine and the Skybox may have the same balance problems for grid people. Just too small. 

    For my clients offgrid, the CSW is a good spare/back-up for an XW+. Only the best as there will be few to help in remote places offgrid.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Raj174Raj174 Solar Expert Posts: 648 ✭✭✭✭
    ewb,  
    In XW inverter (NA) will not have this balance issue with most home loads because it is a large enough inverter/charger.
    The same with a 4kw radian from outback and its 8kw version.
    Think about it, most homes have a 100 to 200 amp service and you are either powering a 30A inverter/charger or a 60A.
    Which one will have issues?
    This is not a new problem because in the old days it was pretty common knowledge. I think it is great that folks have got this too work reasonably but, what a pain. It also looks somewhat unsafe to have all of these components laying there. It should be all in one box, in my opinion. A home insurance inspection would have issues with a complicated home power system. I have seen them fail for insurance.

    If I was not so busy right now before winter I would add this dilemma to the FAQ section in the forum here. It might help someone make the best decision for their situation.
    Dave, I can assure you that the Radian GS4048A does not have any issues with load balancing. That function of the inverter may be built in due to it costing 700 dollars more than the equivalent CSW. In the two and a half years I have been using the GS4048A, I have not experienced any of the issues that MrM1 has described in his posting. In fact, I don't remember this being an issue with the old XW 4000,
    although I'm sure you know that inverter better that any of us. 

    Rick  
    3600W PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 207AH LiFePO4 no BMS, 4500W genset.
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,125 ✭✭✭✭
    edited October 18 #54
    Several of the ones I work on do and from my Wrench solar installers there are a bunch. 
    What loads do you run? They have problems with 120V well pumps, water heaters, and bathrooms.
    You are also selling to the grid and many of the ones I see are being used in grid apps where they can't sell.

    What is the XW4000?


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    I am not qualified to answer or respond to the path this discussion has taken,  but concerning my experience and install ... if the CSW's size is what you need ...

    1. Even adding an autotransformer at the typical price point found on most seller web site,  the CSW + PSX-240 still costs less than a comparable Outback Power inverter of the same / similar size and the Outback would not be 240v unless stacked. 

    2.  I did experiment with Load Shaving both with the AT and without the AT and even setting the "load shaving amp" set to 1 amp - the lowest setting allowed - AC support still preforms better than load shaving as to how much power is drawn from solar/batteries and how much power is drawn from the grid.  So unless you need the timer,  that would throw the CSW back to drawing all power from grid,  AC support mode works better

    3.  As to safety,   not sure I was clear,   My final install did NOT leave everything laid out on the table (as in the testing pics). 
    - The MidNite Solar E-Panel was closed up
    - The PSX-240 was mounted on the wall under the E-Panel
    - The PSX-240 was closed up in it's metal case
    - #8 THHN wire in the correct colors and ground (EGC) was run thru Flex conduit from the E-Panel to the PSX-240
    - This still might not satisfy the insurance company because of the complex electrical system,  but it might be a bit safer than pictured above. (sorry I might have left the impression that the pics was how it would be installed)

    4. Another much more cost effective method for drawing more from renewable energy would be to simply use a timer on the AC input for the CSW so that it daily disconnects from the grid input thru the day.  And run AC support mode at night.  With the CSW the larger the loads become,  the more AC support mode tends to work even if the loads are unbalanced.

    5.  As to personal costs,  its a long story,  but the PSX-240 basically costs me nothing,  so it was worth a try. 

    Please tell me if I am doing things in a not safe way.  I want to know and would change things based on recommendations. You never need insurance if you don't burn the house down in the first place.

    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,125 ✭✭✭✭
    You are doing fine in my opinion. Just get it all buttoned up so it looks as normal as possible to an untrained eye. It does not hurt to have a fire extinguisher and smoke detector for these people.

    Insurance, do not get me started. Even the Mafia knew how to sweeten the pain. 

    Rick, the problem that is had with the CSW (and any small inverter relative to the loads) is the AC pass thru. If grid assisted, it does reduce the balance problems by keeping the balance better in sell mode. Balance of a home panel is one of the most basic electrician skills.

    The CSW is a 30A passthru. The Radians are 50A and the new Sky box is 60A. I guess you were referring to the XW4024 which also was 60A pass thru. It too had problems with balance in systems but because it could sell, it was less noticeable for grid folks.

    For offgrid, all of this was very rarely a problem because people who live offgrid would not run these kinds of loads, intentionally.


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    edited October 18 #57
    Thanks Dave for the tips. Here is the final as it was finished up the day after testing pics were taken . A smoke detector I have (in the room connected to an alarm monitoring service too), a fire extinguisher I need to get.




    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • MrM1MrM1 Registered Users Posts: 305 ✭✭✭
    As to sizing,  I am only using the CSW for critical loads.  I never intended the system to
    1. run my whole house, 
    2. be an off grid system or
    3. save me money. 
    It is a 3400 watt generator,  plain and simple.  And designed to be available when power goes off after disasters etc.   I do not have the system running thru the main load panel,  I have isolated the critical loads thru an add on Reliance Controls 510c Pro/Tran 2 transfer toggle panel so I can toggle the critical loads from grid to inverter on a circuit by circuit level. 
    My only goal in supplementing my grid connection with the CSW and battery/solar is to save enough on the monthly power bill to buy new batteries in 4-5 years.  So far in one year of operation (system went online Oct 15, 17) I have generated 2.3 megawatts,  which equates to about a $300 dollar per year savings off my power bill ... or $300 x 5 = $1500 ... more than 4 Trojan L16 435ah batteries (I got them for $1265).  If I can keep from destroying them in less than 4 years I am on track to replace them with the savings.
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,125 ✭✭✭✭
    That sounds reasonable M1. It is a good value for a CSW.

    The insurance comments are from total losses and inspections which get done alot out west now with the fires. One may never get the chance to claim a loss as an insurance inspection will have pictures and they may cancel before one has a loss. Many have such high quotes that they self-insure and sink the premiums into prevention of fire.

    I have had a few agents call and tell me to look really carefully at the power system even though the fire guys told me it started on the other side of the house near the laundry room. They are looking to not cover the insured. Once they hear it is offgrid, I may get called because of the business name. Many times they do not know that the home is offgrid when they cover it.

    I would casually inquire at your building department (do not let them get your name) if plastic conduit is allowed inside the structure. 
    Many want metal if this is a garage. I can't remember where your power system is. 
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Raj174Raj174 Solar Expert Posts: 648 ✭✭✭✭
    @Dave Angelini
    Sorry, I was referring to the XW 4000 watt inverter, specifically the XW4048. Also, I don't and never have sold to the grid. I use Grid Zero and Mini Grid only.

    What I'm referring to, is the issue that many posters have with the CSW not pulling a significant amount of amperage from the batteries with an unbalanced load on the inverter when in AC support mode. The Radian GS4048, like the CSW in AC support, also draws 1 amp at 240V while in Gris Zero mode, however if a 500 watt load is placed on L1 while L2 only has a 200 watt load, the total supplied by the batteries will be about 500 watts. In other words, when the load is above 240 watts, the batteries supply power to the loads even if the load is unbalanced, up to the inverters capacity to handle unbalanced loads, which is about 50% I believe, and an autotransformer is not necessary. If you say that other 4000 watt Radians have this same problem, then I will consider myself fortunate, but I haven't seen any posts on the Radians having this issue.

    Rick  

          
    3600W PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 207AH LiFePO4 no BMS, 4500W genset.
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