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[Solved] How to connect the OFF-GRID 1-F inverter in a 3-P installation with a circuit by

rademenes787 38568 42
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How should an AZO Digital ESB off-grid inverter be wired into a 3-phase house installation so it powers only a separate circuit without overloading the inverter, and should its earth/neutral be bonded to the existing grounding system?

Wire the ESB to a separate protected circuit after the main switch, bond the inverter N to PE at the meter/switchboard as the TN-C to TN-CS split, and do not ground the PV DC conductors; only the panel frames/structure and the inverter housing get PE [#20093464][#19848114][#20108698] The inverter has no galvanic isolation and no PE on the AC output, so the AC side behind it should be treated like a TN-S arrangement with RCDs and overcurrent protection on the inverter-fed branch [#19848114][#20093464] One working example connected the inverter feed from the meter bus through an extra small switchboard with protections, then disconnected the chosen house circuit from the main board and reconnected that circuit to the inverter output [#20093464] A phase-switch failure was attributed to incorrect N wiring, specifically not having the N path arranged as expected before the inverter output came up [#19688494]
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  • #31 19696121
    rademenes787
    Level 6  
    Posts: 103
    Help: 1
    Rate: 25
    Maverick73 wrote:
    rademenes787 wrote:
    ... a bit of a mistake that the inverter is 24V and not 48.


    I have 3 converters (ultimately there will be 4) for 12V and I think that I don't need either 24V or 48V. Each converter has its own, as I write it, service area. I don't load one device.
    The system is running nice ... fridge, automatic machine, computer, TV, lighting and other ... batteries practically constantly charged .. this is a support, not a power factory.


    Wow, what an interesting solution. Why 3 or 4? Different for each phase or what? What inverters? What schematic?
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  • #32 19697115
    Anonymous
    Level 1  
  • #33 19697198
    rademenes787
    Level 6  
    Posts: 103
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    Rate: 25
    Maverick73 wrote:
    My vision and execution. I also have 3-F at home and it only uses one phase. Each inverter has something under it, e.g. one only for a washing machine, the machine has a power consumption of up to 1800W, a 2000W sine inverter ... cool. The next ones have other devices that do not exceed the maximum power consumption. Any unforeseen situation will eliminate only one circuit ... just like the fuses in the house ... one short circuit one fuse, you do not lose power in the whole house ... right.
    And there are other good sides of such a solution ... e.g. the inverter will break down ... you are waiting for a repair or you have to buy a new one and there is no electricity ... in my case, the others always work in this case, as well as with the batteries one of the 4 rains but 3 are still working... and there can only be one with the same capacity as 4pcs.
    I do not need any phase switches or similar, for me this role is played by a comparator and a 2P 5V RM84 8A relay.
    The failure of your PF-441 costs PLN 300 and my RM84 PLN 3 ... 4kWh from panels and the cost of RM returned ...
    I don't have schematics because I do everything from my head ...
    That's it ...


    Well, you can anyway. This is probably a good approach, but the devil is in the details. I'd probably miss a lot from you, but probably not everything. If you say 3 or 4 inverters, how many panels do you have? each inverter has dedicated panels? Maybe when it comes to equipment failures, it would be enough to have a second spare? After all, your inverters probably did not give away for free, so you have the cost of the inverter x4. You'd have to sit down and count. At the moment, I estimate with the processing of the dashboard about 12 thousand. When it comes to the phase switch, it's a nice toy, I burned PLN 300, but I found a nice replacement for PLN 200, it does everything the same and has additional regulations. Meanwhile, the poor guy on fire is waiting for a couple of varistors and a circuit board, maybe we can resuscitate him ... (cost PLN 20). The issue of batteries, it also annoys me a bit that I have to buy identical ones and buy them in pairs, instead of what I can get .. well, the whole point is to find a golden mean here on the electrode.
    Greet and wait for a reply.
    PS I started the system with a new phase switch and after removing the above-mentioned fault, everything sucks. The only thing that on these cloudy days the production is = "0"
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  • #34 19697311
    Anonymous
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  • #35 19697435
    rademenes787
    Level 6  
    Posts: 103
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    Well, apart from the fact that it's 21 used panels versus my 8 new 370W panels, it's probably an impressive result. I definitely need to do some digging to get the most out of my system. I don't think it's the inverter's fault that it produces electricity or not? What are your inverters?
    I am also thinking about joining the well-known el-car system for heating water, but rather on the principle of "switching" to such an inverter due to the small number of panels ...
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    #36 19697533
    Anonymous
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    #37 19847904
    Read76Write
    Level 6  
    Posts: 5
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    Hello dear group members,
    I have a question for rademenes 787.
    Is the N output of the ESB finally grounded? I.e. the TN-CS installation with N and Pe separation in the main one goes to the circuits?
    Do they work in this configuration?
    It's kind of interesting because:
    1. ESB series inverters do not have galvanic isolation, therefore there is no PE output on the AC output link.
    2. The lack of galvanic isolation means that with a correct system (no damage) everything can work, but if:
    a. you have grounded pv modules and the insulation of the panels is punctured, the inverter may catch fire
    b. you do not have a grounded pv installation, in the absence of galvanic isolation, in my opinion N at the output of the inverter may "float" (there may be differences in potential in relation to the ground), so I am very interested in whether you have grounded N from the ESB output??

    Thank you in advance for your answer.

    ps
    galvanically isolated inverters from the same manufacturer appeared. HSB series
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    #38 19848114
    rokbok
    Level 40  
    Posts: 4315
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    Read76Write wrote:
    a. you have grounded pv modules and the insulation of the panels is punctured, the inverter may catch fire


    This is not the case with the grounding of the panels, the panels themselves, i.e. their housing/frame and the structure on which the panels are placed, can be grounded, only solar wires must not be grounded, neither plus nor minus in the absence of galvanic isolation, as stated in the "Safety Instructions" " in the Off Grid ESB inverter manual, point 11, quote. The inverter does not have galvanic isolation. Do not ground the power cables of the PV installation, it may damage the device."
    After that, the ESB is additionally connected to the ground using a dedicated screw on the housing.
  • #39 19849796
    Read76Write
    Level 6  
    Posts: 5
    Help: 1
    Rate: 1
    It's a bit about that and a bit not.
    Fact:
    1. The ESB has no galvanic isolation
    2. ESB has no constant phase output!!!
    ...which makes the whole project very dangerous. Plugging into the inverter installation in this way may result in serious consequences.
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  • #40 19855596
    stlis
    Level 2  
    Posts: 4
    Hello and welcome to the topic

    I'm thinking about connecting an off-grid ESB inverter in SUB mode, i.e. supporting energy from panels with energy from the power grid.
    So my question is, do I need to report this?
    Such inverters are supposed to be Off-Grid, but the support is directly on the AC line.
    What if the support works, because 1kW is flowing from the PV and 0.5 kW is selected from the grid and the production from PV will increase to 3.0 kW? Will overproduction go to ZE?
    And what, for example, when the support works and there is no voltage from the ZE?

    How to connect the OFF-GRID 1-F inverter in a 3-P installation with a circuit by
  • #41 20093464
    przemom42
    Level 4  
    Posts: 7
    Rate: 1
    When there is no voltage from the ZE, as you have batteries or the sun, the ESB will power the house. After all, you connect the ESB right after the main switch, of course, through the protection, and from the ESB it goes to the home installation (you can imagine it as a serial connection. If there is no voltage, you power the house like with UPS and that's it. The disconnection is in the inverter. Grounding is provided separately from the ground (not with PENA), i.e. you have to make PE yourself and do not connect PENA with ZE with N behind the inverter. You are making a kind of TN-S network in one word. There are normally RCD protections behind the inverter, etc. So the topic seems to be quite safe. Unless I don't understand what my colleague wants exactly, it seems that the instructions say quite precisely about powering the house with ESB inverters.

    By the way, I have a question, is it possible to unearth the PV modules, i.e. remove the plate that bites into these modules? and do you need to insulate the biting place of this grounding pad with some tape?

    Regards
  • #42 20108698
    rademenes787
    Level 6  
    Posts: 103
    Help: 1
    Rate: 25
    Read76Write wrote:
    Hello dear group members,
    I have a question for rademenes 787.
    Is the N output of the ESB finally grounded? - YES, i.e. it is connected in the switchgear with the PE cable at the meter, so "as if"
    I.e. the TN-CS installation with N and Pe separation in the main one goes to the circuits? - Exactly as written above
    Do they work in this configuration?
    It's kind of interesting because:
    1. ESB series inverters do not have galvanic isolation, therefore there is no PE output on the AC output link. - there isn't. But my ground connected to N on the board goes to a pin in the ground anyway for potential equalization
    2. The lack of galvanic isolation means that with a correct system (no damage) everything can work, but if:
    a. you have grounded pv modules and the insulation of the panels will be punctured, the inverter may catch fire - well, I guess there's nothing more I can do about it. I will now be using this installation as a UPS in the event of a power outage. I recently joined ON-GRID
    b. you do not have a grounded pv installation, in the absence of galvanic isolation, in my opinion N at the output of the inverter may "float" (there may be differences in potential in relation to the ground), so I am very interested in whether you have grounded N from the ESB output?? - yes

    Thank you in advance for your answer.

    ps
    galvanically isolated inverters from the same manufacturer appeared. HSB series
  • #43 20108699
    rademenes787
    Level 6  
    Posts: 103
    Help: 1
    Rate: 25
    Read76Write wrote:
    Hello dear group members,
    I have a question for rademenes 787.
    Is the N output of the ESB finally grounded? - YES, i.e. it is connected in the switchgear with the PE cable at the meter, so "as if"
    I.e. the TN-CS installation with N and Pe separation in the main one goes to the circuits? - Exactly as written above
    Do they work in this configuration?
    It's kind of interesting because:
    1. ESB series inverters do not have galvanic isolation, therefore there is no PE output on the AC output link. - there isn't. But my ground connected to N on the board goes to a pin in the ground anyway for potential equalization
    2. The lack of galvanic isolation means that with a correct system (no damage) everything can work, but if:
    a. you have grounded pv modules and the insulation of the panels will be punctured, the inverter may get burned - well, I guess there's nothing more I can do about it. I will now be using this installation as a UPS in the event of a power outage. I recently joined ON-GRID
    b. you do not have a grounded pv installation, in the absence of galvanic isolation, in my opinion N at the output of the inverter may "float" (there may be differences in potential in relation to the ground), so I am very interested in whether you have grounded N from the ESB output?? - yes

    Thank you in advance for your answer.

    ps
    galvanically isolated inverters from the same manufacturer appeared. HSB series


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Topic summary

✨ The discussion revolves around connecting the AZO Digital ESB-6kW-24V inverter in a 3-phase installation while addressing concerns about its capacity to handle high loads, particularly in a kitchen drawing 4 kW. Users share their experiences with hybrid and off-grid systems, emphasizing the importance of proper grounding and circuit separation to avoid overloads and ensure safety. The conversation highlights the need for careful configuration of the inverter's output connections, particularly regarding the neutral (N) and protective earth (PE) connections. Various battery options and their capacities are discussed, along with the implications of using different inverter brands and models. Users express concerns about the profitability of off-grid systems compared to hybrid setups and share insights on optimizing energy production and consumption.
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FAQ

TL;DR: AGM batteries drop to 60 % capacity after 400 cycles [Elektroda, kosmos99, post #19675114]; “OFF-Grid is not profitable, but it is convenient” [Elektroda, kosmos99, post #19674285] Correct TN-CS bonding and right-sized battery fusing stop burned phase switches and fires. Why it matters: One wrong neutral or earth connection can destroy a PLN 300 switch in seconds.

Quick Facts

• ESB-6 kW-24 V inverter supplies ≈3 kW continuous [Elektroda, rademenes787, post #19647178] • Growatt SPF 5000 outputs 5 kW and lets you bond N-PE in software [Elektroda, kosmos99, post #19647871] • AGM batteries lose ~40 % capacity after 400 cycles at 50 % DoD [Elektroda, kosmos99, post #19675114] • 24 V, 3 kW string needs ≥125 A DC fuse (I=P/V) [NEC 240.4] • 3 kWp array can yield up to 10 kWh on a clear summer day [Elektroda, kosmos99, post #19675114]

Can I bond the inverter’s neutral to PE in a TN-CS home network?

Yes. Forum tests show ESB neutral bonded to the existing PE/PEN bar works without trips when the link occurs only once in the main board [Elektroda, rademenes787, post #20108698] Do not create multiple bonds or you risk RCD nuisance.

Why did my PF-441 phase switch burn out?

The neutral was taken from the inverter bus instead of the grid. When the inverter delayed output, the switch had no reference and toggled rapidly until it exploded [Elektroda, kosmos99, post #19688494]

What fuse size should I install between batteries and a 24 V, 3 kW ESB inverter?

Current equals power divided by voltage: 3000 W ÷ 24 V ≈ 125 A. Select a 150 A class-T or ANL fuse to handle surge yet protect wiring [NEC 240.4].

Is a 24 V system a mistake compared with 48 V?

For powers above 3 kW, 48 V halves battery current and lets you use thinner cables and smaller fuses. Users called the 24 V choice “a bit of a mistake” after needing double battery strings [Elektroda, rademenes787, post #19676282]

How much battery capacity keeps pumps and a fridge running overnight?

Loads of 150 W (pumps) + 100 W (fridge) for 9 h need 2.25 kWh. A 24 V, 200 Ah AGM bank gives 4.8 kWh but only 2.4 kWh at 50 % DoD, matching the target [Elektroda, rademenes787, post #19676282]

Will the ESB inverter back-feed the grid when in SUB/Support mode?

No. The ESB lacks grid-tie approval and disconnects export. When PV exceeds load it simply throttles or diverts to resistive heaters [Elektroda, kosmos99, post #19855596]

Do I have to notify the utility if I use SUB mode?

Notification is not required because the inverter has no grid-feed function. However, many utilities still request written confirmation that no export occurs. Check local regulation G98/UL1741 as applicable [E-ON Small-Scale Guide].

Should I earth PV module frames with a non-isolated ESB?

Yes, bond the aluminium frames to a dedicated PE conductor. Never ground the DC+ or DC– conductors; the manual forbids this because there is no galvanic isolation [Elektroda, rokbok, post #19848114]

What happens on a cloudy winter day even with oversized panels?

A 3 kWp array may produce only 0.5 kWh when irradiance drops below 100 W/m². “Cloudy or winter day with snow and the next day there is already a problem” [Elektroda, kosmos99, post #19674486]

How can I split household loads across multiple small inverters?

One user runs three 12 V, 2 kW units, each feeding a dedicated circuit such as washing machine, IT, or lighting. If one fails, only that branch goes down and spare parts cost PLN 3 per relay, not PLN 300 per phase switch [Elektroda, Maverick73, post #19697115]

How-To: stop neutral faults when wiring a phase switch

  1. Run L and N from the utility side to the NO/NC inputs.
  2. Feed the phase-switched output with both L and N from the same source.
  3. Tie inverter N only on the load side, never at the relay inputs. Follow up with continuity test before energising [Elektroda, rademenes787, post #19678407]
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