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Growatt 48v 3000 Open Neutral

Warning!!! The following is an extrapolation of what I think the system looks like..... I could be wrong.

I looked up Reliance transfer switches and they all seem to only switch the Hot line and not the neutral line.

With that in mind, I sketched out what the circuit might look like. Please look it over and let me know if this seems accurate to you.

1635728509114.png

Assuming this properly represents the circuit, a few things jump out at me.

1) First, there is a ground loop (dotted green in the image below). The ground wire between the growatt and xfer switch (red X) should be disconnected. The transfer switch and downstream circuits are adequately grounded with just the connection to the main panel. The ground loop is not likely to be causing the GFCI to pop but there is a small chance that disconnecting the marked ground wire could mask the problem.

Note: The AC-Ground in and AC-Ground out is tied together on both the GFCI and the Growatt.

1635728606811.png

Once the ground loop is taken care of, it will look like this:

1635728797406.png

2) The next thing I noticed is that there is only one NG bond in the system. When the xfer switch is wired as shown above that single bond will always be seen, regardless of whether the power is coming from the Growatt or grid. This explains why the tester shows OK when the xfer switch is in place but shows an error when the xfer switch is not wired in.

3) Finally, the Neutral from the Main Box is tied to the Neutral out of the Growatt. This means the Neutral-in of the Growwatt and the Neutral-out of the Growatt are tied together. I don't know what the Growatt will do in this situation, but I suspect this is the root cause of the GFCI poping. I am going to have to think about what could be done to fix this.

Meanwhile, try this:
With all loads switched to Off in the transfer box and the inverter on UTIL.... does the GFCI pop?
With all loads switched to Off in the transfer box and the neutral disconnected as shown below, does the GFCI pop when in UTIL mode?

1635731576631.png
 
Warning!!! The following is an extrapolation of what I think the system looks like..... I could be wrong.

I looked up Reliance transfer switches and they all seem to only switch the Hot line and not the neutral line.

With that in mind, I sketched out what the circuit might look like. Please look it over and let me know if this seems accurate to you.

View attachment 70949

Assuming this properly represents the circuit, a few things jump out at me.

1) First, there is a ground loop (dotted green in the image below). The ground wire between the growatt and xfer switch (red X) should be disconnected. The transfer switch and downstream circuits are adequately grounded with just the connection to the main panel. The ground loop is not likely to be causing the GFCI to pop but there is a small chance that disconnecting the marked ground wire could mask the problem.

Note: The AC-Ground in and AC-Ground out is tied together on both the GFCI and the Growatt.

View attachment 70950

Once the ground loop is taken care of, it will look like this:

View attachment 70952

2) The next thing I noticed is that there is only one NG bond in the system. When the xfer switch is wired as shown above that single bond will always be seen, regardless of whether the power is coming from the Growatt or grid. This explains why the tester shows OK when the xfer switch is in place but shows an error when the xfer switch is not wired in.

3) Finally, the Neutral from the Main Box is tied to the Neutral out of the Growatt. This means the Neutral-in of the Growwatt and the Neutral-out of the Growatt are tied together. I don't know what the Growatt will do in this situation, but I suspect this is the root cause of the GFCI poping. I am going to have to think about what could be done to fix this.

Meanwhile, try this:
With all loads switched to Off in the transfer box and the inverter on UTIL.... does the GFCI pop?
With all loads switched to Off in the transfer box and the neutral disconnected as shown below, does the GFCI pop when in UTIL mode?

View attachment 70966
@FilterGuy I had fly out of town for work yesterday, but will bet able to test this Friday when home. Do you want me to perform two tests? 1)Just in UTIL mode with all loads off in TransSwtich and no ground and same test with ground disconnected AND disconnecting neutral and reply back with behavior?
 
@FilterGuy I had fly out of town for work yesterday, but will bet able to test this Friday when home. Do you want me to perform two tests? 1)Just in UTIL mode with all loads off in TransSwtich and no ground and same test with ground disconnected AND disconnecting neutral and reply back with behavior?
yes
 
I have the same Growatt, only 24V version, connected to the BlueSea circuit breaker box. ( https://www.amazon.com/gp/product/B08SHHC9J6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 https://www.amazon.com/gp/product/B0000AXNUY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 ) and I have the same problem.
When measured on the cables coming out of the GroWatt, I am getting
G/N 58V,
G/L 51V,
L/N 120V.
When I turn on Blue Sea circuit breaker, it changes to:
G/N 151V,
G/L 148V and
L/N 120V.
Also the "Reverse Polarity" light goes dimly ON.
Connecting heat gun, 1200W, I am getting 10 amps on L and N and zero on G.
When I short G and N, everything goes to normal: G/L 120V, N/L 120V and G/N 0.
I even connected G and N with 15 ohm resistor, or automotive 12V bulb, I've got a little spark, bulb didn't lite and measuring were correct:
G/L 120V, N/L 120V and G/N 0.
So... Can I just wire them together? Maybe using small circuit breaker, or resistor?
 
I have the same Growatt, only 24V version, connected to the BlueSea circuit breaker box. ( https://www.amazon.com/gp/product/B08SHHC9J6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 https://www.amazon.com/gp/product/B0000AXNUY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 ) and I have the same problem.
When measured on the cables coming out of the GroWatt, I am getting
G/N 58V,
G/L 51V,
L/N 120V.
When I turn on Blue Sea circuit breaker, it changes to:
G/N 151V,
G/L 148V and
L/N 120V.
Also the "Reverse Polarity" light goes dimly ON.
Connecting heat gun, 1200W, I am getting 10 amps on L and N and zero on G.
When I short G and N, everything goes to normal: G/L 120V, N/L 120V and G/N 0.
I even connected G and N with 15 ohm resistor, or automotive 12V bulb, I've got a little spark, bulb didn't lite and measuring were correct:
G/L 120V, N/L 120V and G/N 0.
So... Can I just wire them together? Maybe using small circuit breaker, or resistor?
Could you provide a diagram of how things are wired?
 
Growatt has inlet from batteries, PV and shore power and outlet 120V AC, three wires, L,G and N. Those three comes to BlueSea circuit breaker panel - like illustrated on the picture above.
 
Is shore power also hooked to the breaker box? If I am following the description correctly, the output of the Growatt is tied to shore power at the breaker box. That seems very wrong.
 
This is the way growatt says the bonding should be handled.

1636915610092.png

When in Line mode (Power from the grid) the Neutral bond from the grid is 'passed through'
When there is no AC or the inverter is in Battery mode, the relay is Off and therefore provides the NG Bond.
 
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BTW, In the above diagram, The "AC Load" would be the breaker box and the "Independently Derived power source" is Shore Power.
 
@FilterGuy
Finally getting back to this testing. I found this bit of information in a separate thread about Conext Inverter and Transfer switch. I think this aligns with your thoughts that only the hot needs to be passed from the inverter since the neutral and ground are already bonded at the main panel and the neutral is already in place for the existing circuit.

Screen Shot 2021-11-14 at 3.26.39 PM.png
 
Is shore power also hooked to the breaker box? If I am following the description correctly, the output of the Growatt is tied to shore power at the breaker box. That seems very wrong.

No, shore power and Inverter are connected via transfer switch, before breaker box: https://www.amazon.com/gp/product/B00153EYTO/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

This is the way growatt says the bonding should be handled.
I don't have option 24 in my menu, and that makes connection you illustrated impossible? But let me ask you that: Can I just add to my system relay which would bond G and N together whenever I would use power from the batteries? External relay powered and/or controlled not by Growatt, but by incoming signal from L line from my transfer switch?
 
No, shore power and Inverter are connected via transfer switch, before breaker box:
I really need a schematic of your system..... I am not following the description.


I don't have option 24 in my menu, and that makes connection you illustrated impossible?
I have seen other reports that option 24 is missing. Just to confirm: Do you have the SPF 3000TL LVM?

I don't have access to an LVM24 right now so I can't play with it..... but here is a long shot:

I notice that option 23 is only available when the unit is switched off:

1637046088276.png

Could it be that option 24 does not show up either? Try switching it off and see if both 23 and 24 show up.

Can I just add to my system relay which would bond G and N together whenever I would use power from the batteries? External relay powered and/or controlled not by Growatt, but by incoming signal from L line from my transfer switch?
Like I said, I really need a schematic to answer the questions.
 
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@FilterGuy Still have not had time to test with my TS switch as you recommended, but i found a video where a US Supplier of these Growatt inverters recommended to a customer to simply always leave in permanent jumper between AC Input and AC Output Neutral. Seems to solve both open ground/floating neutral as well as load on ground. Keeps everything bonded back at main panel. Thoughts on this?
 
@FilterGuy Still have not had time to test with my TS switch as you recommended, but i found a video where a US Supplier of these Growatt inverters recommended to a customer to simply always leave in permanent jumper between AC Input and AC Output Neutral. Seems to solve both open ground/floating neutral as well as load on ground. Keeps everything bonded back at main panel. Thoughts on this?
The only thing that worries me about that is how well the growatt will handle having the Neutral in and out tied together. I would ask Growatt about that.
 
@FilterGuy
Here is the video. It was recommended by Ian at watts247.com.
As long as the inverter is OK with the Neutral in and Neutral out being connected then this works for a stationary install.

On a mobile install, there still needs to be a dynamic bond.
  1. When on shore power, use the bond in the shore power monument.
  2. When no Shore power, use a local bond.
What must be happening, is that the inverter is turning on grid power before switching the dry contact. This results in a momentary condition of having two N-G bonds. That results in current on the ground which, in turn, results in the GFCI popping.
 
I really need a schematic of your system..... I am not following the description.

I don't know how to draw schematics, but my system is as simple as it can be. Shore power goes to Growatt and power from pure sine inverter goes to Growatt. Those lines are connected in automatic transfer switch: Inverter is connected to Growatt all the time, unless shore power is on. When I connect shore power outlet, switch cuts off power from inverter and connects shore power to Growatt. PV goes to PV inlets in Growatt and batteries are connected to battery outputs in Growatt. From Growatt line goes to circuit breaker box.

IMG_3217.JPG


I have seen other reports that option 24 is missing. Just to confirm: Do you have the SPF 3000TL LVM?

I don't have access to an LVM24 right now so I can't play with it..... but here is a long shot:

I notice that option 23 is only available when the unit is switched off:

Yes, I do have SPF 3000TL LVM. I was looking for option 24 when Growatt was off, but no cigars. I've found option 23, but there is no 24.

IMG_3208.JPG
 
As long as the inverter is OK with the Neutral in and Neutral out being connected then this works for a stationary install.

On a mobile install, there still needs to be a dynamic bond.
  1. When on shore power, use the bond in the shore power monument.
  2. When no Shore power, use a local bond.
What must be happening, is that the inverter is turning on grid power before switching the dry contact. This results in a momentary condition of having two N-G bonds. That results in current on the ground which, in turn, results in the GFCI popping.
If I am correct about what is going on, then there is a problem with mobile set-ups because the system may or may not be on shore power.
If the You-tube video is correct and it is OK to connect Neutral-in and Neutral-out, then this may be a solution for a mobile set-up.

1637108375564.png
With this arrangement, if there is no shore power, the relay creates the N-G bond. When there is shore power the bond is broken and neutral is connected to shore power. Notice that there can never be a time when there is both a shore power bond and the local bond.

WARNING: I have not built and tested the above circuit....
 
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