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aleuli avatar image
aleuli asked

Making Enphase IQ connected with AC input work with the Multiplus in ESS

Hi all, My system is 1.8Kw panels with enphase IQ microinverters and enphase envoy controller. I have the enphase set to no export with two CTs on the grid input. That works fine with no issues.

The system has to be AC coupled, I added a Multiplus 48/3000/35-50, 220V and used a 32A Victron autotransformer to get the split phase system to work properly. also have 8 x 6v GNB Marathon Element AGM batteries.


My issues with the system are:


*Optimized Without "Batterylife" mode, the charger doesn't reset after a discharge to minimum SOC, so effectively stays all the time to the latest status it had(eventually remains in float forever), Here in my region I don't like Batterylife changing the "active SOC limit" on daily basis because some days are cloudier than others. But cant use it without Batterylife, because the problem with charging.


*The Enphase no export limit seems to be around 50W, this cant be changed, so I had set the ESS "Grid setpoint" to 120W. During day time, after the ESS detects loads getting under the grid setpoint, it does start charging, but immediately enters self consumption any time the loads are greater than panel generation. This keeps interrupting the charge on cloudy days, there is some claims that is better to charge the batteries to 100% before using them on the next cycle.

The solution could be using a schedule to set the daytime as charge only, not allowing self consumption to kick in. And also for the inverter to use the battery when the tariffs are higher, or to allow the batteries to rest in float mode for a while(there is also claims on this to be good for the batteries). Basically something that tells the system when it is allowed to kick in the inverter.

A work around I found is setting the "Maximum inverter power" to 0W every night after battery is discharged to "Minimum SOC", with "Limit inverter power" enabled. Then I have to set it back up for the inverter to start back. But I see no reason why couldn't be automated.


*When the grid is gone the Enphase envoy seems to command the microinverters to shut down, because it does detect 0 Watts on the grid input. I had to manually change the enphase profile to allow export, for them to come back to life. I plan to test a relay that activates a load to trigger the current transformers to report a fixed load above the grid setpoint on the envoy. I think I have to wrap several turns around the CTs to achieve this with minimum load.


Regards

Alex V.

DR


ESSmultigrid
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

I think it is going to be difficult to get the system working well when there are multiple grid meters looking at the grid and making decisions that impact the others based on that.

Can you wire your system so that the Enphase is connected to the AC output of the Multi and instead only use the Victron meters to manage?

Or is that not possible with the split phase grid arrangement?

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Is my understanding that ESS cant limit the export to the grid from the panels. So I need the Enphase Envoy to do that. And so far the system works as long as grid power does not fail. All my suggestions are about the Victron system charge management and power assist, I want to automate setting the charger not to kick in until charge is full, and schedule the inverter power assist.

For when the grid fails I plan to do a hack and will post about my findings. I understand the Victron system cant control the Enphase on any way, their system seems to be quite closed. However they do have the ability for frequency to power control, I did set the frequency settings on the ESS assistant: https://enphase.com/sites/default/files/downloads/support/Design-Considerations-AC-Coupling-Micros-Battery.pdf

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perma-batteries avatar image
perma-batteries answered ·

Hello Aleuli,


In other words, you've got your system AC coupled now with the IQ7+ on the AC-OUT of the Multi, and having the zero export feature of the envoy activated and properly regulating the micros right ? Once the system is in islanding mode, you have to set up in the ESS assistant a PV inverter on the output such that it can throttle the power output of the MO accordingly (in function of the SOC). Enphase to my knowledge doesn't have a specific grid country that is fit in that case (just like it would be for example in a Fronius with the MG50 setting), so you'd have your MO gradually reducing their power output, and then decoupling at 51.5 Hz...

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