Multiplus 2 powerlimited to 600W: Critical load power limiting behavior?

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Jannes Peschel asked Feb 7, '23

Multiplus 2 powerlimited to 600W: Critical load power limiting behavior?

I have an Multiplus II 48/3000 GX as the core of my ESS. All the PV is DC coupled with SmartSolar. The Multiplus is connected grid parallel. The EM24 is used for energy metering. Due to german laws, I have limited the inverter power to a maximum of 600W.

Recently I added a possibility to connect devices to the AC Out of the MP2. When I have a full battery I disconnect the MP2 from the grid and run it in inverter mode to supply loads with more than 600W like the dishwasher.

The thing I can't get my head arround is the behavior of the MP2 in the case I leave the grid connected and run a critical load at the output with e.g. ~2000W. Then the MP2 runs with a power of something between 1000W and 2000W and i still use 300W to 900W from the grid, althought the MP2 is not running at full power. It is not a transiant behavior. I would have expected the MP2 either to

stay at a limited power of 600W since it is still grid connected or
to fully supply the cirtical loads and limit the AC IN power to maximum of 600W. (In this case run at full power with 2400W)

Has someone experience with this scenario and can explane this behavior to me?

Multiplus-II feed-in limit

mp2.jpeg (104.5 KiB)

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Alexandra ♦ commented · Feb 08, 2023 at 05:29 PM

@Jannes Peschel

To clarify here...

You have three phases coming into the home - all three metered and reporting to the GX.

The MP 2 supplies loads on one phase.

What is measuring critical loads separate to the other AC loads?

What is the EM24 position set as?

If you set your inout current limit down on the inverter it will help not go over your grid set point of 600W.

But is seems as though something else is not right.

Is everything on the latest firmware?

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Jannes Peschel Alexandra ♦ commented · Feb 08, 2023 at 09:29 PM

"You have three phases coming into the home - all three metered and reporting to the GX."

Correct, by the EM24.

"The MP 2 supplies loads on one phase."

Yes, on L1.

"What is measuring critical loads separate to the other AC loads? "

The Multiplus itself.

"What is the EM24 position set as?"

What do you mean by position? It is configured as "grid meter". It is located in the fuse box to measure the incomming energy from the grid.

"If you set your inout current limit down on the inverter it will help not go over your grid set point of 600W."

The "Input current limit" is set to 3A.

Not quite sure what you mean with grid set point? My "grid set point" in the ESS settings is set to 10W. My "maximum inverter power" is set to 600W.

"Is everything on the latest firmware?"

Everything is up to date, except the MP2. It is on V500 and the most recent version is V501. I don't think it is a problem. V500 is from december 2022.

Which behavior of the MP2 would you consider normal in my scenario?

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ess-settings-1jpg.jpg (36.7 KiB)

ess-settings-2jpg.jpg (33.3 KiB)

Modifications Space

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Answer 1 · 2023-02-13T16:25:04Z

Jannes Peschel answered · Feb 13, 2023 at 04:25 PM

The solution to my problem is as follows:

I had configured the shore limit to 3A. When using loads at the AC OUT of the MP2 as large as 2000W the 600W inverter limit was conflicting with the 3A (=690W) shore limit. Since 600W inverter power plus 690W shore power (=AC IN) results in 1290W total power at AC OUT. The Multiplus 2 in this case decides to prioritise the shore limit over the inverter limit and fills the cap between 1290W and 2000W by increasing the inverter power.

I have now modifed my settings to achieve the desired behavior of the Multiplus:

I have removed the inverter limit of 600W completly and changed the shore limit to 2.8A to achieve the 600W AC-IN power limit to comply with german law for small self build solar systems.

Removing the inverter limit now enables me to power loads up to 2400W without a problem at the AC OUT of the MP2 using solar or battery power. While at the same time beeing able to compensate up to 600W of the grid parallel loads.

Would the same have been possible with the option to limit system feed-in power? I did not find a clear anwser to the question whether the feed-in limit limits the total power over all phases to the set value or the power on the one phase the MP2 is connected.

shore-limit.jpg (50.2 KiB)

no-limit.jpg (46.3 KiB)

vrm.jpeg (93.2 KiB)

feed-in-limit.jpg (41.2 KiB)

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