MultiPlus-II 48/5000: Active AC Input in "disconnected" state.

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loxley asked Oct 16, '21

MultiPlus-II 48/5000: Active AC Input in "disconnected" state.

Hi all,

We've been running a MultiPlus-II system for about 16 months now.

Our MultiPlus-II 48/5000 recently started not accepting the AC Input connection (after an 'overload' event - we get these overload shutdowns from time to time, for some reason).

The system has a Venus GX , at Firmware v2.73.

The MultiPlus is on firmware version 475. It's configured as a single unit.

ESS is set as 'external control' (I automatically/dynamically set the grid setpoint through MQTT).

The MultiPlus detects the AC input voltage and frequency fine:

Here are some VE.Bus state entries for the event in question (power off due to overload occured at 10:38):

AC In voltage and frequency is stable, both before and after the time of fault:

Any idea what could be causing this sudden loss of accepting AC in? Could it be an internal fault (main grid relay) ?

Multiplus-II fault

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Answer 1 · 2021-10-17T00:38:36Z

shaneyake answered · Oct 17, 2021 at 12:38 AM

First thing I would do is update the firmware to the lastest is 487 and see is that fixes it.

Next thing to check is your wiring, make sure everything is tight. If the inverter fails to track the grid correctly then you tend to see this behavior. This can be caused by bad/lose wiring, so of the older firmware versions have a harder time with this then the new ones.

Hope that helps.

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loxley commented · Oct 18, 2021 at 07:22 AM

Hi Shaneyake,

Indeed, that is what seems to have fixed it (firmware update to 487)! It was exhibiting very odd behaviour before that though (when set to 'charge only (II on the power rocker switch)', it did accept the grid connection after about 5 minutes, to start charging the battery).

The wiring was checked and all good.

Also, regarding the random overload / shutdowns, when I took a look in VEConfigure, there was a warning about high grid voltage. I do have 2 Schneider PV inverters on AC in, that seem to put out quite a high voltage (high 250s.). This is still below the local grid code, and below the 267v max for the Multiplus. Hopefully the new firmware fixes that issue too!

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