Solar edge 11.4 on high leg shutting down

Update:

Heard back from solar edge and here is what they said:

"This was all reviewed by our Senior Engineer and this is his feedback: The drawing package shows all 4 inverters connected to the neutral. Only one of the inverters would be able to connect to the neutral. We need to make sure that all inverters are disconnected from the neutral and set to 240 no neutral country codeā€


All inverters do have a neutral connection currently, I don't know what the country code was set to. I did look through the installation manual, and it does seem like there is not a clear explanation of neutral or not, country code, and grid type. It's all kind of strange. They definitely need better instructions here.

The solar contractor should be going down there this week to make those changes and we'll see what happens.
 
electrofelon said:
Please elaborate
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Inverters connected to the high leg and the neutral will not see 120/240V, they will see 208/240V and that is not what they expect to see. It's why the manuals will prohibit the neutral connection on delta xfmers with a center tap.
 
pv_n00b said:
Inverters connected to the high leg and the neutral will not see 120/240V, they will see 208/240V and that is not what they expect to see. It's why the manuals will prohibit the neutral connection on delta xfmers with a center tap.
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A few points .

1. I still don't understand and have never gotten an explanation of when or why inverters need a neutral connection.

2. It seems to me, just thinking about it logically, that it shouldn't matter whether a neutral Conductor is connected to the inverter's neutral terminal. If the inverter is set to a certain grid type that doesn't need or can't reference the neutral, then why can't it just disregard any measurements off that terminal??

3. Unless I missed it, the solar edge manual does a horrible job in describing when to make a neutral connection.
 
electrofelon said:
I do not know the specifics of the 5 minute grid qualification procedure. I dont think they are 'pinging" the grid with any output, but that is a total guess.
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We do a commissioning test for the 5 minute period.
There are some companies that change the meter, walk away and forget it.

It shouldn't export for 5 minutes after startup, grid bliink, etc.
It should have an export switch or setting to stop it from exporting altogether also.

If it's feeding loads in the house then of course it can start anytime.
 
electrofelon said:
1. I still don't understand and have never gotten an explanation of when or why inverters need a neutral connection.
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If the grid type programmed into the inverter requires confirming the L-N voltages.

electrofelon said:
2. It seems to me, just thinking about it logically, that it shouldn't matter whether a neutral Conductor is connected to the inverter's neutral terminal. If the inverter is set to a certain grid type that doesn't need or can't reference the neutral, then why can't it just disregard any measurements off that terminal??
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That seems correct, but apparently the inverters in question were not set to such a grid type, per your post #82.

Cheers, Wayne
 
wwhitney said:
If the grid type programmed into the inverter requires confirming the L-N voltages.
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But there isn't consistency here. For example some single phase 120/240 inverters require a neutral, some don't, and some can be set either way. When you say "require" is this just something that is up to each manufacturer so some do it differently and it's not specifically laid out in something like UL 1741?

That seems correct, but apparently the inverters in question were not set to such a grid type, per your post #82.

Cheers, Wayne
Click to expand...

You comment doesn't agree with What the solar edge engineer said. Note he said to disconnect the neutral. I assume that means physically disconnect it.
 
electrofelon said:
Update:

Heard back from solar edge and here is what they said:

"This was all reviewed by our Senior Engineer and this is his feedback: The drawing package shows all 4 inverters connected to the neutral. Only one of the inverters would be able to connect to the neutral. We need to make sure that all inverters are disconnected from the neutral and set to 240 no neutral country codeā€
Click to expand...
Yeah thats what I have done in the past, the inverter thats on A-C gets a neutral, the others don't, solar guy sets the firmware to '240 no neutral country code'
I remember the neutral because on one job in particular I initially did not put a neutral on the plan to the A-C inverter and we were asked to go back and pull one later and it was my mistake.
It only has to be sized to be an EGC I am told there is never a load on it.
I would ask that senior engineer about the 'open phase'.
 
electrofelon said:
But there isn't consistency here. For example some single phase 120/240 inverters require a neutral, some don't, and some can be set either way. When you say "require" is this just something that is up to each manufacturer so some do it differently and it's not specifically laid out in something like UL 1741?
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That's a very good question. I may take a gander at UL 1741.

electrofelon said:
You comment doesn't agree with What the solar edge engineer said. Note he said to disconnect the neutral. I assume that means physically disconnect it.
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Well, he also said to reprogram the inverters. So whether the neutral disconnection is necessary after the inverters are reprogrammed is not clear to me. Perhaps it was just added on "for good measure". But it's not unreasonable for an inverter programmed to expect a 2-wire 240V grid, no neutral to notice that a neutral is connected to it and to therefore say the grid configuration isn't right. That's a conservative behavior for the programming.

Cheers, Wayne
 
It would be interesting to deep dive into how grid tie inverters work, they are very proprietary about how they make them, there is a forum member on here who is or was a firmware engineer possibly @suemarkp .
I suppose one could read a bunch of patents or look at how a open source inverter works.
 
@electrofelon
Are you saying that the AB and BC inverters had neutrals run to them? I certainly wouldn't have done that or at least would have questioned it if I saw it on the plans. The high leg to neutral voltage could only cause a problem.
 
wwhitney said:
That's a very good question. I may take a gander at UL 1741.
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OK, I took a quick look at UL 1741. As far as I saw, the only relevant requirements were to comply with IEEE 1547 and 1547.1.

So I took a quick look at IEEE 1547. Some relevant excerpts are below. I didn't look to see if it specifically address connecting single phase inverters to three phase systems.

Cheers, Wayne

Definitions:

applicable voltage: Electrical quantities that determine the performance of a Local EPS or DER specified
with regard to the reference point of applicability, individual phase-to-neutral, phase-to-ground, or phase-to-
phase combination and time resolution.

NOTEā€”Applicable voltages are used as a synonym for applicable frequency, which can be derived from the
applicable voltages.

4.3 Applicable voltages

The applicable voltages (32) determine the performance of a Local EPS or DER and are the electrical
quantities specified with regard to the reference point of applicability, individual phase-to-neutral, phase-to-
ground, or phase-to-phase combination and time resolution.

For DER with a PCC located at the medium-voltage level, the applicable voltages shall be determined by
the configuration and nominal voltage of the Area EPS at the PCC. For DER with a PCC located at the
low-voltage (33) level, the applicable voltages shall be determined by the configuration of the low-voltage
winding of the Area EPS transformer(s) between the medium-voltage system and the low-voltage system.
The applicable voltages that shall be detected are shown in Table 1 and Table 2. For multi-phase systems,
the requirements for applicable voltages shall apply to all phases.

[Table 1 omitted]

Table 2 ā€”Applicable voltages when PCC is located at low voltage
Low-voltage winding configuration of Area EPS transformer(s) (a)Applicable voltages
Grounded Wye, Tee, or Zig-Zag (b)Phase-to-phase and phase-to-neutral, or
Phase-to-phase and phase-to-ground
Ungrounded Wye, Tee, or Zig-ZagPhase-to-phase or phase-to-neutral
Delta (c)Phase-to-phase
Single-Phase 120/240 V (split-phase or Edison connection)Line-to-neutralā€”for 120 V DER units
Line-to-lineā€”for 240 V DER units (d)

(a) A three-phase transformer or a bank of single-phase transformers may be used for three-phase systems.
(b) For 120/208 V two-phase services, line-to-line voltages shall be sufficient.
(c) Including delta with mid tap connection (grounded or ungrounded).
(d) Sensing line-to-neutral on both legs of a 120/240 V split-phase or Edison connection effectively senses the line-to-line and is therefore compliant with this requirement. Sensing line-to-ground may also be used; however, the ground connection should only be used for voltage sensing purposes.

(32) Applicable voltages are used in synonym for applicable frequency, which can be derived from the applicable voltages.
(33) 1000 V and less per IEEE Std C62.41.2 and IEEE Std C62.45.
 
jaggedben said:
@electrofelon
Are you saying that the AB and BC inverters had neutrals run to them? I certainly wouldn't have done that or at least would have questioned it if I saw it on the plans. The high leg to neutral voltage could only cause a problem.
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Yes I believe all had a neutral run and connected. In the solar installers defense, solar edge doesn't seem to say when to connect a neutral.
 
Update: solar contractor changed the setting and removed the neutral and it's working! I would like to know if physically removing the neutral was necessary, but we will never know. I don't really blame the solar contractor, solar edge's manual is incomplete and vague in this area. Also the plans showed a neutral connection, so really it would be whoever drew the plans' fault.
 
In a center tapped delta the neutral point is not common to the phase pairs AB and BC, so i could see the inverters being confused if they were concerned with L-N.
I cannot speak of the design issue of ignoring the neutral if the system configuration does not support it, however it does not surprise me if the L-N voltage check still occurs regardless of the setting.
I guess I am jaded with software and electronic engineers that do not understand the basics of power systems even though that is where their products are being employed.
 
jim dungar said:
In a center tapped delta the neutral point is not common to the phase pairs AB and BC, so i could see the inverters being confused if they were concerned with L-N.
I cannot speak of the design issue of ignoring the neutral if the system configuration does not support it, however it does not surprise me if the L-N voltage check still occurs regardless of the setting.
I guess I am jaded with software and electronic engineers that do not understand the basics of power systems even though that is where their products are being employed.
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I guess I am a little conditioned to assume things need a neutral. It seems like the vast majority of PV inverters have required a neutral, although in recent years there seems to be a few more that don't (note some use the EGC for the neutral measurement). Of course I understand the difference in L-N voltages on a 120/240 three phase system, but I wouldn't assume that an inverter wouldn't require a neutral just because of that. It's just a matter of the programming and what the inverter is looking at and expecting.
 
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