EG4 AC Coupling Fronius

[SolarCzar]

@millsan1 Been talking with EG4 Support and SS support and not making progress. After turning to the forums, I see that you have a setup similar to mine and wondered if you would share your settings for your 18k's?

Here's my problem...I have 2x 5kW Fronius inverters on the GEN port of each of my 18K's. I have followed the book on AC Coupling setup, but it's not providing power to the GEN port whereby the grid-tie Fronius inverters would not believe they are in "islanding" mode and sync up. I have 10kW on 2x Fronius, and 30kW on my 2x 18K's. When sun is shining, I want to power house loads, charge batteries, and sell excess back to the grid (I have been net-metering for 15yrs). Sun goes down...run off batteries until discharge limit (what % is best?), then pull back from grid.

I've gone through 4x people at SS and EG4, and they say my ask is "unique". I know that can't be. Any help?

 

[DIYrich]

In the smart load tab, did you check AC coupled to Gen, or whatever the equivalent for the EG4?

The fronius should be in parallel, and that goes into both gen ports.

 

[zanydroid]

I have followed the book on AC Coupling setup, but it's not providing power to the GEN port whereby the grid-tie Fronius inverters would not believe they are in "islanding" mode and sync up.

This doesn’t make sense. With a correct configuration, when on grid these should see grid AC and not have any reason to think they are islanding.

Have you busted out your multimeter and tested the VAC on the gen port?

I've gone through 4x people at SS and EG4, and they say my ask is "unique".

LOL. Maybe the inverter brand name. Maybe try asking again but pretend you are an Enphase user?

 

[zanydroid]

Another idea is to try tying the Fronius elsewhere (the Gen port is for Microgrid forming, you can tie elsewhere while having the power available for self consume). That would be.

Utility meter - CTs - busbar

With EG4 and fronius both backfeeding the busbar.

This quite likely will exceed 120% rule but you can at least rig up a temporary setup and see if you are making progress.

The more elegant way is to figure out the Gen port, but I always like multiple paths to get a solution.

 

[SolarCzar]

So I had them in parallel on my grid main panel on separate breakers. Whole home wiring schema as laid out in EG4 manual with feeder tap (Polaris splice on grid main disconnect). Both worked independently but not together. Was on the phone with EG4 at the time and started sucking battery down. Like 10% in 2min. Shut off the Fronius. They have been working great for 15 yrs.

So yes, I put a multimeter on the port. 0.0 VAC.

 

[zanydroid]

Do you have a picture? I think I get it but pictures are easier. And settings screenshots will help other owners help you. This is likely a settings/programming issue. Note also there are special settings accessible only to EG4 to push down to you. And there are EG4 support folks on this forum you can tag.

(I don’t own this particular one inverter).

So you want to get the Gen port in the right mode to be closed and get VAC out. 0VAC feels like they are off or in generator mode.

You probably want one fronius into one 18kpv because of the need to have the charger capacity be high enough to absorb the max grid tie output. I doubt this will trigger safeguards when on grid (since this safety is not needed) but maybe they try to be super safe.

Another less safe (and maybe warranty violating) but easy way to try is to backfeed through the EPS / AC output port. Some hybrids will properly detect the power coming in and absorb it. The AC will certainly be present to turn on the GTI. The downside is that it is not what the programming expects and it loses the emergency overload drop capability when on the gen port

 

[SolarCzar]

So I've got tons of pics, but getting it packaged where the forum will allow me to upload is tough. Every iPhone pic is huge. So here's the pdf files. Only two of the 4 Fronius inverters are online. They were attached to the Grid panel right of meter in the pic in parallel. I included pics of the multimeter tests as well

I've messaged @millsan1 who indicated his is working. Hopefully, I can get a look at his settings, but I can't tell where mine are wrong. @EG4-Jacob was trying to help and Signature Solar reps haven't been able to figure it out either and say what I'm doing is "unique". After reading on the forum, that is clearly not the case.

Maybe @SignatureSolarJess or @SignatureSolarPeyton or @SignatureSolarJames can help.

Maybe it's the new firmware load. I don't know

 

[1201]

So I've got tons of pics, but getting it packaged where the forum will allow me to upload is tough. Every iPhone pic is huge. So here's the pdf files. Only two of the 4 Fronius inverters are online. They were attached to the Grid panel right of meter in the pic in parallel. I included pics of the multimeter tests as well

I've messaged @millsan1 who indicated his is working. Hopefully, I can get a look at his settings, but I can't tell where mine are wrong. @EG4-Jacob was trying to help and Signature Solar reps haven't been able to figure it out either and say what I'm doing is "unique". After reading on the forum, that is clearly not the case.

Maybe @SignatureSolarJess or @SignatureSolarPeyton or @SignatureSolarJames can help.

Maybe it's the new firmware load. I don't know

Total Battery discharge only 7.3kwh? Is your battery only used when grid is down?

If your battery stays at 100% ac couple will not work. You have it set to disconnect at 95%

 

[SolarCzar]

Those settings are what another user here had set his.

My Perfect setup? I’d like to run the house on PV and charge battery while sun is shining, use the battery when the sun goes down, until best discharge rate, then pull from the grid to power the house (not the battery) and then start over.

So now I'm confused on the settings...If I set AC Couple to start at 100%, then where do I stop? Can it be blank/null?

 

[1201]

Those settings are what another user here had set his.

My Perfect setup? I’d like to run the house on PV and charge battery while sun is shining, use the battery when the sun goes down, until best discharge rate, then pull from the grid to power the house (not the battery) and then start over.

So now I'm confused on the settings...If I set AC Couple to start at 100%, then where do I stop? Can it be blank/null?

You have to set both start and stop. For now set to 5% and 100% and see if the gen connection wakes up.

After that we'll work on getting your house running on battery at night.

 

[zanydroid]

Those settings are what another user here had set his.

My Perfect setup? I’d like to run the house on PV and charge battery while sun is shining, use the battery when the sun goes down, until best discharge rate, then pull from the grid to power the house (not the battery) and then start over.

So now I'm confused on the settings...If I set AC Couple to start at 100%, then where do I stop? Can it be blank/null?

Is smart load on? I don’t understand how the buttons indicate on/off state in the UI.

Which settings that impact the generator port did you double check?

Shouldn’t a lot of these battery threshold settings be irrelevant when grid is up?

 

[SolarCzar]

Changed AC Couple Start to 5% and Stop to 100% and no GEN power

 

[zanydroid]

There is theory of operation description in section 4.8 page 25 which covers the theory I’ve discussed above. How does the observed system behavior jive with the theory written there?

The on grid behavior if set up correctly (per one of the early paragraphs) is for gen port to be paralleled to grid, so 240VAC should show up

 

[SolarCzar]

There is theory of operation description in section 4.8 page 25 which covers the theory I’ve discussed above. How does the observed system behavior jive with the theory written there?

The on grid behavior if set up correctly (per one of the early paragraphs) is for gen port to be paralleled to grid, so 240VAC should show up

I completely agree, but I've got no power on either GEN port of my two 18kpv's. I would think one of them could be a hardware issue, but both tell me it's a software issue. The manual and others on this forum have indicated it works. I've got 0.0 VAC on both devices

 

[zanydroid]

I’ve searched through half the manual and haven’t seen a description of how the settings for mutually exclusive usage (AC couple, smart load, Gen) of Gen port interact. This is a software behavior kind of thing (of course the hardware could also be busted. Like dead gen relay)

Really could use senior EG4 support here…

 

[zanydroid]

Anything in the “History Event” log?

 

[zanydroid]

Changing to Smart Load disable will more aggressively tell the software not to use GEN for smart load and instead use it for AC couple.

The grid always on also has a theoretical interaction



You have grid sellback off, this quite complicates the desired Behavior and the hybrid software may conservatively disambiguate by turning off AC coupled strings.

Do you get the same access to settings via App UI surface as via Web UI surface?

Apologies if I misinterpreted the state of the UI, I don’t own this inverter and am doing my best guess.

 

[SolarCzar]

Busted relay was my first guess...but both relays? unlikely, but no improbable.

As for logs...none. Here is the "data history", but nothing looks relevant. The forum does not allow me to upload excel files

 

[1201]

Changed AC Couple Start to 5% and Stop to 100% and no GEN power

Is your battery currently at 100%? Is it being charged from the grid?

 

[zanydroid]

Busted relay was my first guess...but both relays? unlikely, but no improbable.

As for logs...none. Here is the "data history", but nothing looks relevant. The forum does not allow me to upload excel files

Yeah, both relays being broken is lower probability than some common software or config brainfart.

Another far left field idea that went through my head was whether AC coupling with stacked 18kpv's inverters was tested/implemented by EG4