Planning a new installation

DIY
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1

I have just got my MultiPlus-II 48/3000/35 and have not yet begun the installation. The standard use case will be buffering solar input.

Normal operation

The planned wiring is:

                         Home / Grid
                              |
                       Changeover switch
                              |
                       MultiPlus AC IN
                              |
              +---------------+---------------+
              |                               |
          AC OUT 1                         AC OUT 2
              |                               |
     Emergency sockets                Solar microinverters
     Changeover switches              (physically switchable)
     for refrigerator circuit
     and Home Assistant circuit
     (normally open)

In normal operation I want the MultiPlus to do no autonomous energy management. The charge/discharge power should be specified by Home Assistant and updated approximately once per minute.

I also plan to use a relay on the remote on/off input to switch the MultiPlus off during long winter nights.

Question: What additional hardware/interface do I need to control and monitor the MultiPlus from Home Assistant? I am considering Modbus TCP, MQTT or another well-supported interface. In particular, do I need a GX device, Venus OS, or something else?

Emergency operation

For a prolonged grid failure I plan to use a petrol generator:

                  Petrol generator
                         |
                  Changeover switch
                         |
                  MultiPlus AC IN
                         |
              +----------+----------+
              |                     |
          AC OUT 1               AC OUT 2
              |                     |
     Emergency sockets       Solar microinverters
     Changeover switches    (physically switched OFF)
     for refrigerator
     and Home Assistant
     circuit (connected)

I do not want to rely on the microinverters responding correctly to generator frequency changes. Also, there is a risk that the generator might still be running if I am not paying attention. Therefore AC OUT 2 will be physically switched off while the generator is running.

The generator can run for relatively short periods (about one hour) at high load and reasonable efficiency. The MultiPlus should regulate battery charging according to the load requirements.

Grid failure

In the event of a grid failure I do not want the MultiPlus to automatically create an island.

I want the MultiPlus to turn off and remain off until I have manually made the necessary connections/switch settings and then deliberately restart it for emergency operation.

Question: Is this operating concept achievable with the MultiPlus-II 48/3000/35? If so, what additional hardware, settings or interfaces are required?

Could you please point me to the relevant manuals/documentation? There seem to be a great many Victron PDFs, and I would particularly appreciate references to the documents relevant to this specific setup.

Danke
Axel Berger

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