question

nicov avatar image

Virtual Switch with ESS

Short version:

What is the impact of disabling the AC_1_in on a Multiplus II with the virtual switch in an ESS system?


Long version:

I have two systems, each with a Multiplus II 48/5000. Each has a single Narada 48NPFC100. The battery is generally sufficient for my requirements, with very little taken from the grid. My consumption doesn't justify additional battery purchases. However, the battery goes into protection mode the moment the output current exceeds 100 A.

We have pretty unstable grid supply. If the grid drops when there is no solar input, the battery often goes into protection mode with an overcurrent alarm. If I switch off the grid input via circuit breaker before the grid drops (it is loadshedding, so pretty predictable), the battery and inverter stays up. So basically, the battery really doesn't like that moment between where the grid drops and where the anti-islanding relays open. Also, the battery then struggles to boot up the Multiplus unless there's an additional powersource (grid comes back or power from the panels).

My plan is to use MQTT with a scheduler to disconnect the grid a few mintues before loadshedding is scheduled to start, and to then reconnect it after loadshedding is over. Any reasons why I can't use the virtual switch to do so? The rest of the time I'm perfectly happy with my ESS setup - it is only when the grid drops at night that I have issues.

ESSvirtual switch
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To add to my question:

1. Is it even possible to switch the virtual switch via MQTT? I've looked at all my captures of topics, and can't find anything that seems applicable.

2. In the System Setup settings, there are options to make AC_1 "Not available", "Grid", "Generator" or "Shore Power". What does "Not available" actually do? If set to "Not available", will the system still see the grid as a load for that bit of time before the anti-islanding kicks in?

1 Answer
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @NicoV

you can set the Multi to 'inverter only' to disconnect AC input.

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Thanks, Daniël! That works - now I just have to do the coding.