question

cajanus avatar image
cajanus asked

Self-consumption Assistant has started setting Ignore AC, turning off grid.

Hi,

I have a simple single-phase MP Compact 24/2000/50 which is AC-coupled to a 2kW Fronius MPPT. Batteries are 300Ah NiFe.

I have been using the self-consumption Hub-2 V3 Assistant (0168) for 10 months. Five months ago, I noticed on my power bill that the Assistant hadn't been "disconnect from grid at night"-ing as advertised so I started manually turning off the grid at sundown.

For the past few days, the Victron has started setting Ignore AC to 1 after I turn the grid on in the morning, disabling export of excess PV power to the grid.

If I delete the Assistant, Ignore AC goes off (0) and I can export PV. So it's not a hardware or grid problem?

However, on cloudy days, I can't charge the batteries as, without the Assistant, it starts importing power from the grid to charge them. Inefficiencies x Inefficiencies x Inefficiencies. Oh, for a NEVER-EVER-CHARGE-BATTERIES-FROM-THE-GRID flag!

Today I upgraded VEConfig3 and tried the latest version of the Hub-2 V3 Assistant, (0182). Same problem.

Any ideas what might have suddenly triggered this behaviour after 10 months?


Possibly related: New NiFe batteries need to be conditioned with high currents so for the past 4 months (it took me a while to find this out) I've been manually turning on the charger when PV power reaches 1500W to give them 42A for a few hours/day.


Assistants
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2 Answers
cajanus avatar image
cajanus answered ·

So it doesn't look like anyone else has seen this problem.

The Assistant is still setting Ignore AC whenever I add it back as a test.

Are there diagnostics I can run on my MultiPlus?

Should I just send it back to be serviced? Not a good time of year to get a quick turn-around.

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Alexandra avatar image Alexandra ♦ commented ·

@cajanus

It may be rejecting grid because of high or low voltage or maybe frequency? What are those settings on grid tab?

Grid can also be rejecting if the input impedance has changed.

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colin-foster avatar image colin-foster commented ·
I have a similar setup to yourself but using CSS instead of hub 2. Do you have a GX device on your system? Wales UK
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cajanus avatar image
cajanus answered ·

Thanks for your interest, Alexandra.

Umains=235V, Freq=50.1Hz both well within acceptable tolerances. I've seen it happily accept 245V in the past. Grid tab has disconnect voltages of 180V and 265V.

I just tested it twice: add Assistant, MP resets, 30seconds later it sets Ignore AC. Delete Assistant, no problem.

How does one measure grid input impedance?

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