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Andy avatar image
Andy asked

Output of Phoenix Smart Inverter feeds AC input of Multiplus II (Off-Grid). Possible?

I currently have a Phoenix Smart inverter 48/3000 and also just got a Multiplus II 48/5000 delivered.

The interesting question arose if I can use the smart inverter as the AC input of the Multi and activate Power Assist in the assistant. Obviously I have to turn of the charger in the Multi.
Both inverters are connected to the same battery which is charged from MPPTs only. There is no grid connection at all and no AC coupled solar.

The Multi can handle all sort of AC inputs from what I understand, so would such piggy-back solution work? It should synchronise to the Smart inverter's output, right?

Thanks,
Andy

Multiplus-IIPhoenix Inverter
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Alexandra avatar image
Alexandra answered ·

@Andy from the Off-Grid-Garage

Hi Andy. I have enjoyed keeping up with your YouTube channel, always on the lookout for the next installment.

They will synchronise, so it could work (definitely not supported officially). Make sure your input current limit is low enough not to overload the Phoenix. And yes disable the charger.

The other consideration is can the battery (the heart of the system) bank handle the full loads (current draw) of both the inverters and SOC with a BMV or shunt also needs to be there to keep that story straight. Not sure how you will communicate that to the phoenix.

I know this will answer the questions of many on this forum. This type of setup is often proposed. ;)

A similar setup is the cascade where there are two banks, two inverters one feeding the other. Many interesting system proposal ideas here if you are ever looking for crazy backyard experiments for the channel.

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Andy avatar image Andy commented ·
Thanks so much for your reply, @Alexandra!


The battery will be 48V/864Ah (~45kWh), so that shouldn't be a problem to handle them both. I also have a smart shunt running in the system and all devices are connected to a VenusOS device. Later, the BMS will also report back to Node Red to contribute to the system and overall functionality.

I'm not planning to run this system on full power a lot, it is just for these few times a day when all the pumps are running at the same time for 10min or so.

I would set the input current of the Multi to relatively low value so the Phoenix has enough reserve capacity when it gets hot down here.


Also, thanks a lot for watching my videos, much appreciated :)

Thanks again for your answer.

Andy


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