Signature Solar and the EG4-6000EX-48HV

[dcg9381]

Basically it depends on your Loads

Can you provide a little more information? I understand that if I had more load than PV power, that it'd down shift to the next source in the priority list. At what point would it shift back to solar? When there is zero load, less load, etc?

I believe these inverters won't "dual source" - meaning if they're on battery, they're pulling from battery and PV power is not going anywhere. Is that correct?

 

[Zwy]

How does grid passthrough work with EG4 6000EX, if it has isolation transformer?

Here is what @FilterGuy determined given the information in the thread. https://diysolarforum.com/threads/eg4-6000ex-double-ground-neutral.50908/post-672602

Does it pass grid through to 240V primary, so output is still isolated?

It appears to be isolated.

Does it pass grid through to transformer secondary? If so, does secondary then act as an auto-transformer and try to rebalance grid? Or does it disconnect center-tap when passing through?

Good questions, SS has not been forthcoming with information from what I have read.

Does it switch between grid and isolation transformer feeding output?

Yes. However Filter Guy believes it acts as an auto transformer in bypass mode. My opinion is a neutral pass thru.

I was going to say you don't need 3-pole transfer switch, can just used interlocked breakers switching only L1/L2 (and get neutral/ground bond from grid always), but I realized pass through inverter needs to be understood.

It seems it has neutral to the inverter, I would assume for a pass thru when on grid power. Why else have it if it is an isolation transformer?

I do not agree with the common neutral in his diagram, my guess is it creates a situation where it is similar to an autotransformer and will attempt to balance anything on the service side of the grid transformer. I may be incorrect on this, please elaborate if you agree/disagree. I also disagree with the common neutral for the N-G bonding. It has been stated common neutral is not supported for this unit.

Either way, in order to truly isolate the inverter for a complete bypass, such as a failed inverter, repairs/maintenance, I would use a 3 pole transfer to add neutral for the subpanel from grid. I would not use a common neutral. N-G bond should be in the subpanel, one member attempted to charge a Tesla and it would only work with N-G bond in the subpanel. I believe relying on the main service panel N-G bond without a common neutral is due to the inverter does not bond N-G and with an isolation transformer it needs the bond at the subpanel. Input neutral is switched and thus there isn't any path back to the main service panel N-G bond. It is slowly coming together how these work, it would be much easier if SS provided the information needed including an internal schematic in the manual.

 

[FilterGuy]

Here is what @FilterGuy determined given the information in the thread. https://diysolarforum.com/threads/eg4-6000ex-double-ground-neutral.50908/post-672602



It appears to be isolated.


Good questions, SS has not been forthcoming with information from what I have read.



Yes. However Filter Guy believes it acts as an auto transformer in bypass mode. My opinion is a neutral pass thru.


It seems it has neutral to the inverter, I would assume for a pass thru when on grid power. Why else have it if it is an isolation transformer?

I do not agree with the common neutral in his diagram, my guess is it creates a situation where it is similar to an autotransformer and will attempt to balance anything on the service side of the grid transformer. I may be incorrect on this, please elaborate if you agree/disagree. I also disagree with the common neutral for the N-G bonding. It has been stated common neutral is not supported for this unit.

Either way, in order to truly isolate the inverter for a complete bypass, such as a failed inverter, repairs/maintenance, I would use a 3 pole transfer to add neutral for the subpanel from grid. I would not use a common neutral. N-G bond should be in the subpanel, one member attempted to charge a Tesla and it would only work with N-G bond in the subpanel. I believe relying on the main service panel N-G bond without a common neutral is due to the inverter does not bond N-G and with an isolation transformer it needs the bond at the subpanel. Input neutral is switched and thus there isn't any path back to the main service panel N-G bond. It is slowly coming together how these work, it would be much easier if SS provided the information needed including an internal schematic in the manual.

You may be correct. EG4 just released a new video

Newer models of EG4 6500ex are built without the bonding screw

I just looked at this Conext manual https://documents.unboundsolar.com/media/schneider-conext-xw7048e-export-inverter-installation-manual-3551255610.2430072-2.pdf and those Schneider models do not switch neutral so this will be interesting. Then there is this thread, the Schneider does not bond...

diysolarforum.com

The video says their inverters will pass through neutral in pass-through mode. While watching the video I started wondering if it applies to the Low Frequency inverters and then at about the 3 min mark they talked about the new firmware for the 6000W unit.

@BenFromSignatureSolar Can you confirm that with new firmware the EG4 6000EX will pass through the neutral in battery mode?

 

[Hedges]

I do not agree with the common neutral in his diagram, my guess is it creates a situation where it is similar to an autotransformer and will attempt to balance anything on the service side of the grid transformer. I may be incorrect on this, please elaborate if you agree/disagree.

I would rather the relay did not put center-tapped secondary across grid L1/L2/N. Although, I find it doesn't take much wire for resistance. to balance the equalizing between an auto-transformer and something else.

Inverter could be designed internally to isolated (at least some of) transformer leads, but we don't know for sure.

I still can't see why external N connection to everything would be any problem. 2-pole transfer switch or interlocked breakers should be sufficient.