Inverters not Balancing Selling

Discussion about OutBack Inverters in Grid Tie Applications

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martyzman
Forum Member
Posts: 16
Joined: Mon Mar 12, 2007 11:21 am
My RE system: Mate3S
10 port hub
Port1 - FXR2524A
Port 3 - FM60
Port4 - FM60
Port 5 -FM80
Port7 - FXR2524A
4835 Watts of solar
22 x 12.6 x 88 Ah batteries (24.39 kWh)
System is Grid Tied
Location: Rochester NY

Inverters not Balancing Selling

Post by martyzman »

Hi all,

I have two FXR2524a inverters that I recently updated from GTFX2524 units. They are wired 120 volts Port1 as phase 1 and set as Master and port 7 as phase2 set as Phase 2 Master in the Mate3S. I updated all the settings to be the same on the new inverters through the Mate3S but the new FXR units don't sell as the older units did. With the older GT units the first (port1) Master inverter would sell up to about 4.5 AAC then the second inverter (port2) Classic Slave would pull in and the two would balance selling at 2, 4, 6, or 8 AAC each. With the newer FXR units the second unit (port 7) will start selling and go up to 19.5 AAC before anything happens on the inverter in port1. I contacted support and they suggested swapping phases since the system should start selling on port1(L1) then bring in port7(L2). I did that and now port 1 starts selling but still no balanced selling pull in on the second inverter. Any suggestions on settings that I should check in system or inverter on the Mate3S?
raysun
Forum Emperor
Posts: 9024
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Parallel Stacked, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Inverters not Balancing Selling

Post by raysun »

Forgive me for butting in here, as I am strictly off-grid, and have no direct experience with grid-tied setups and selling to the grid. I do, however, have quite a bit of experience with the FXR class inverters, and similar "lack of balance" issues.
For my understanding - your system is configured for 240V split-phase (series stacked) operation. Under normal and expected circumstances, it would start selling to the grid on one 120V leg via the L1 Master, until a certain current threshold was reached, at which point the L2 Master would start selling and the net current sold to the grid would be balanced between the two inverters.
The FXR inverters are not following this pattern. Rather, the inverters handle selling in an asymmetrical manner, with the inverter originally assigned as L2 Master supplying far more current than L1 Master. When the inverters switched roles (both logically, and physically by changing Hub assignments?), the asymmetric behavior followed the now L1 Master.
Did I get it right?
In my case, with dual FXR3048A inverters configured for 120V single phase (parallel stacked) operation, a seemingly similar "unbalanced" current condition is displayed when on Generator AC Input. The "Slave" inverter habitually overshoots the set AC Input current limit, and regularly draws more AC current for battery charging / load service than does the "Master". When swapping "Master" and "Slave" logically and by Hub port assignments, unlike your case, the condition stays with the "Slave".
Why do I think these two disparate operational misperformances have any relation to each other? Both cropped up with the advent if the FXR class. Both are using the inverter circuitry in an "alternate" mode - other than pure battery inverting to the AC Output. In my, and similar cases, AC Input is being rectified and fed to the battery. In your case, DC Input is being inverted and fed to the AC Input. In both bases, current balance between the two inverters is poorly maintained.
I have worked my version of the FXR issue with other users, and with Outback Tech support for the better part of a year, with no resolution unfortunately. It sounds like you are walking a similar garden path. I have come to conclude the issue is endemic within the FXR architecture, either hardware, firmware, or both. I do not know of any configuration steps, either inverter swapping or parameters via the Mate, that will mitigate or resolve the issue.
It might be time for the villagers to take up pitchforks and torches, mob the castle, and demand this monster be taken back into the lab.
martyzman
Forum Member
Posts: 16
Joined: Mon Mar 12, 2007 11:21 am
My RE system: Mate3S
10 port hub
Port1 - FXR2524A
Port 3 - FM60
Port4 - FM60
Port 5 -FM80
Port7 - FXR2524A
4835 Watts of solar
22 x 12.6 x 88 Ah batteries (24.39 kWh)
System is Grid Tied
Location: Rochester NY

Re: Inverters not Balancing Selling

Post by martyzman »

Hi again RaySun,

My diagnosis so far was to first move the phases in my main power panel, thinking the power creation would move from the Port7 inverter to the Port1 unit. I did this so I wouldn't have to move all the black and red lines in my Outback AC cabinet. Well, nothing changed, still sold out of Port7 inverter. Since the inverters are wired "split phase", each being on a separate AC phase from the street, they seem to be properly 180 degrees out of phase but don't really care what phase they are on to do that. I then moved the control cables to the hub on my inverter1 to port7 and moved inverter2 to port1. After changing the Master and Phase2 Master configs in the Mate3S then I started selling out of Port1 and now have no selling out of Port7. Mark at Outback Support told me that the mate3S is supposed to control the selling for split phase units so I guess that is where the programming / software issue resides. The inverters appear to be dumb operators and only work as Radian units controlling output to both phases if they are wired as 240 volt units. In 120 volt "split phase" mode there doesn't seem to be much "control" anymore in the Mate3S. This sucks if you are trying to operate 240v load units and have enough panels to produce about 5Kw of power like I do. The 240 volt hardware won't get any power on L2 until the Mate3S decides to power the second leg. Kind of dangerous in an off Grid configuration. I would much prefer that the Mate3S brought both inverters online and shared the load AC output from the start, ensuring that any loads on the "output" side of the inverters would be properly driven. I am not sure for a Grid tied configuration in 240 volt mode that the way this system operates is "code" for power production in the state of NY. I am going to investigate this and possibly have the regulators talk with Outback concerning this issue. As an installer and electrician the fact that the wired system never balanced created AC out equally when wired in 240V mode has always bothered me.
raysun
Forum Emperor
Posts: 9024
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Parallel Stacked, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Inverters not Balancing Selling

Post by raysun »

There's definitely something amiss. I worked with Mark as well, and he had some suggestions and insights for my situation, but ultimately no real solution resulted.
I'm a bit suprised, and concerned, about your description of the 240V operation. I'm about to add L2 wiring to my AC infrastructure for 240V split-phase. If "house loads" are balanced between the two legs, I'd expect inverter output to be balanced proportionately. I guess I'll find out.
I'm not holding out much hope, however, that the current imbalance with AC Input from the generator will improve. It is strictly an inverter function, the Mate has no bearing after initial setup.
Admittedly, my ignorance of grid-tie and the Mate's role is vast. Hopefully there's a "silver bullet" there for the selling issue. I'm not sure what odds the Vegas bookies would give, though.
martyzman
Forum Member
Posts: 16
Joined: Mon Mar 12, 2007 11:21 am
My RE system: Mate3S
10 port hub
Port1 - FXR2524A
Port 3 - FM60
Port4 - FM60
Port 5 -FM80
Port7 - FXR2524A
4835 Watts of solar
22 x 12.6 x 88 Ah batteries (24.39 kWh)
System is Grid Tied
Location: Rochester NY

Re: Inverters not Balancing Selling

Post by martyzman »

Well, if your system is parallel stacked and you have your FXR's wired as 240 volt suppliers to your load panel then you should be OK as each inverter should drive both phases. Worst comes to worse I may try the same configuration with my inverters. I am just not sure how this system is supposed to work unless the first would start then the second inverter would drive the line when the first hit its maximum supply wattage. I keep thinking how a 3 phase setup would work and wonder how you would feed a 3 phase load if it only drives one phase until saturation. Not exactly "kosher" if you get my drift. I guess that is why more and more Grid tied configs are going to Micro Inverters so you can drive 240 volts, wire directly to both phases in a consolidation panel then hit the street Power panel with the combined output current. Just downright strange no matter how you slice it.
raysun
Forum Emperor
Posts: 9024
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Parallel Stacked, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Inverters not Balancing Selling

Post by raysun »

The parallel stacked configuration is, of course, strictly 120V AC out. It won't drive a 240V load (like an air conditioner, electric dryer, level 2 EV charger, etc.). For 240V operation, they must be series stacked.
For selling to the grid, it would only feed one leg. I guess that would be OK, the utility may need to weigh in on that.
I'm still surprised the series stacked inverters don't operate more synchronously.
Off the wall questions:
Are the two inverters at the same Power Save Level? (Level 0).
Is Search active on either inverter?
martyzman
Forum Member
Posts: 16
Joined: Mon Mar 12, 2007 11:21 am
My RE system: Mate3S
10 port hub
Port1 - FXR2524A
Port 3 - FM60
Port4 - FM60
Port 5 -FM80
Port7 - FXR2524A
4835 Watts of solar
22 x 12.6 x 88 Ah batteries (24.39 kWh)
System is Grid Tied
Location: Rochester NY

Re: Inverters not Balancing Selling

Post by martyzman »

Port1 - Master PSLevel = 1, Port7 Phase 2 Master PSLevel = 0 ( I had them both at 0, Mark suggested this config)
No search is OFF as far as I can tell. Not sure it would do anything as I only have a radio on the output of one inverter to verify the system is on and supplying power out. Inverters come on and go off depending on Grid Use Time setting.
raysun
Forum Emperor
Posts: 9024
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Parallel Stacked, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Inverters not Balancing Selling

Post by raysun »

martyzman wrote: Fri Nov 11, 2022 1:36 pm Port1 - Master PSLevel = 1, Port7 Phase 2 Master PSLevel = 0 ( I had them both at 0, Mark suggested this config)
No search is OFF as far as I can tell. Not sure it would do anything as I only have a radio on the output of one inverter to verify the system is on and supplying power out. Inverters come on and go off depending on Grid Use Time setting.
That's a bit unorthodox for Power Save levels, IMO. It seems both should be active, instead of the L1 Master "asleep at the switch".
Each inverter will only produce AC output if there is demand on its leg. While a radio may be a load, it may not be enough to pass some internal threshold the inverter needs to see for selling. (Just guessing here.)
What happens if the AC load between the two inverters is more balanced?
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