Growatt SPF-5000-ES AT and N/G solutions

[timselectric]

I hear you. There’s a lot happening with everything in this capacity.

Thanks,
Hopefully, a good working "out of the box " solution is implemented. I would much rather buy from a local distributor.

 

[Trip.Diamond]

Done a little research on the N/G relay inside the inverter. It looks like pin #3 is where you need to solder to. (Please verify this)

Well looks like we have found the difference between the "International" version and the "US" version of the SPF 5000 ES.
International version (yours) has a SHORI 12H-PCS-12 relay the "US" version (mine) has a SHORI 12H-PAS-12 relay. C=double throw A=single throw.

The us version has no connection to the relay at Point #3.

There is a spot on the board for it but no pin attached.

 

[timselectric]

Well looks like we have found the difference between the "International" version and the "US" version of the SPF 5000 ES.
International version (yours) has a SHORI 12H-PCS-12 relay the "US" version (mine) has a SHORI 12H-PAS-12 relay. C=double throw A=single throw.

The us version has no connection to the relay at Point #3.

There is a spot on the board for it but no pin attached.

Hmm
I see

 

[timselectric]

That just makes it even harder.

 

[timselectric]

Well, if the replacement relay still switches between battery mode and grid mode. You can tap the other pin and control your relay in reverse position.

 

[timselectric]

Actually, maybe not.
I believe that the relay is connecting "C" (output terminal) to either "NC" (input terminal) or "NO" (ground, in my case).

 

[timselectric]

You could tap the 12v coil signal for the relay. And use a 12v relay for your auto transformer.

 

[Trip.Diamond]

You could tap the 12v coil signal for the relay. And use a 12v relay for your auto transformer.

That is what I was thinking. Hopefully it has enough current to activate another 12v relay (it should) that I can then use to switch the AT off/on
seems like the only option with this unit.

 

[timselectric]

Yes, that seems to be the only viable option left.
Should be pins 1 & 2. Polarity won't matter.

 

[timselectric]

I find it a bit frustrating that they can swap out a relay, but can't swap out an identification sticker.

 

[abauti1]

First, let's point out the issues with this inverter for use in a split-phase system.

1) this inverter was designed for use in a 230v grounded installation. (European standards)
It's input and output are L1 and "N". This input "neutral" is expected to be grounded by the grid, and at the building service main panel. In bypass mode, this grounded "neutral" is passed through the inverter to the loads panel. In battery mode, the inputs are disconnected and the inverter will internally bond the output "neutral" with the inverter case and ground terminals. (This connects a hot wire to ground, in the US)

When using this inverter in a split-phase configuration. You need 240v single phase ungrounded. Then you use a transformer to create the midpoint tap for the neutral.
This gives you 120/240 split-phase.
This neutral should be grounded at all times, for life safety.

Signature Solar has worked with Growatt to modify the design so that the 2 lines are ungrounded through the inverter. (By removing the grounding system on the main board.) This stops the internal grounding relay from connecting "N" to ground.

2) the use of an AT (auto transformer) , creates the neutral in a very efficient way. And does so in a small package.
It's connected to the loads panel and needs to have its neutral bonded to the ground.
But, if you bond its neutral at the loads panel, you will create a ground loop between the loads panel and the main panel. This happens only when the inverter is in bypass mode. This is undesirable and very dangerous.

To avoid the N/G loop. Run a neutral from the main panel to the loads panel. This neutral is already bonded at the main panel, and provides short protection at the loads panel.
But, this puts the AT in parallel with the grids transformer.
This is undesirable, because the AT can try to carry the loads of the grids transformer.

To solve all of these issues, this is what I have done.

1) I ran a neutral conductor from the main panel to the loads panel. (Not bonded at the loads panel)
This provides a neutral for the loads in bypass mode. And provides the N/G bond from the main panel, in all modes.

2) install a relay on the AT feed conductors. Which is controlled by the inverter grounding relay. To only turn on the AT in battery mode.

To access the inverter grounding relay signal, I connected to the board at the screw location that was designed to ground the output "N" in battery mode.
This was done by a ring terminal and a non conductive nylon 3mm x 8mm machine screw.
And another ring terminal at the internal "L" terminal. This gives me a 240v signal.

Now, the AT is never connected to the loads at the same time as the grid. (No load sharing)

And, the loads panel neutral is always bonded. (From the main panel's N/G bonding point)

I also added another relay between the inverter grounding relay signal and the AT relay.
This keeps the internal inverter power isolated from external power. (This was for my own piece of min

Hi I've been following the N/G discussions on several threads and like the idea of controlling the AT to only turn on in battery mode. I follow that the (unbonded) loads panel has the neutral connected back to the (bonded) main panel, whereby you have only one bonded location during bypass (grid) mode; but should there be a way to bond the neutral and ground at the inverter while on battery mode?

 

[timselectric]

Hi I've been following the N/G discussions on several threads and like the idea of controlling the AT to only turn on in battery mode. I follow that the (unbonded) loads panel has the neutral connected back to the (bonded) main panel, whereby you have only one bonded location during bypass (grid) mode; but should there be a way to bond the neutral and ground at the inverter while on battery mode?

That bonded neutral remains connected, at all times.
In battery mode, it's only providing the bond.

 

[abauti1]

That bonded neutral remains connected, at all times.
In battery mode, it's only providing the bond.

I think I understand. So the N/G bond is only necessary at the main panel so long as one is able to turn the AT off during bypass mode?

 

[timselectric]

Yes
This solved the N/G bonding issue and the autotransformer in parallel with the grid issue.

 

[abauti1]

That's a good solution; you should consider making a video. I couldn't tell from the pictures, is your AT set up in a way that power is cut to the loads panel should it fail and lose the Neutral?

 

[timselectric]

It will be.
I'm in the process of redesign, at the moment.
Overcurrent and loss of neutral protection.

 

[BartHenry]

Yes, that seems to be the only viable option left.
Should be pins 1 & 2. Polarity won't matter.

Is the 12v relay AC or DC.

 

[timselectric]

Is the 12v relay AC or DC.

DC

 

[BartHenry]

DC

Thanks. Could you tap into the relay and use this SSR to drive one leg of the transformer?
SSR-40DA

 

[BartHenry]

Thanks. Could you tap into the relay and use this SSR to drive one leg of the transformer?
SSR-40DA

Actually I think you would need to drive a NC 240v contact and the contact would shut off the transformer... or am I thinking wrong.