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big-blue asked

Basic support Multiplus with Generator and grid connection

Hi, i am new and have a question if my plan is realizable. My plan is to use a Multiplus with a connected generator and solar power to reduce my grid load.

Currently i only have a grid connection with 3 phases and N, i live in Germany.

And my final solution would be this:

Use always the generator source to reduce the load. If the generator does not deliver enough power also use power from the battery which will be loaded from the solar panel and a Victron MPPT solar controller. If these two sources do not have enough power, use grid power.


This is my expectation of the ESS System:

I would expect that ESS of victron with Phase-compensation is able to handle my load and will reduce the grid consumption of my house to zero, as long as the generator power (max input configured in Multi) and Multiplus inverter power is higher than the load of the house.

Is this correct?


If yes, i would expect these devices in my system:

EM24 grid meter

Mutliplus

MPPT solar charger

Batteries


Wiring setup:

Connect the generator to the input of the multi and of course the battery to it. The battery will also used from a Victron MPPT to power up the battery with solar power. Connect the output1 of the Multi to one phase of my House, thats it?


It sounds to easy to be true.


I know there are a lot questions and maybe the headline is also not really helpful, but maybe one of you will help me to get better knowledge of this. Or will post some info where i can get the information.


Thank you very much.

Multiplus-IIGeneratorgrid
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4 Answers
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Mike Dorsett answered ·

Sorry to burst your bubble.. Connecting both a generator and the grid to a multi plus is not possible. You can connect either a generator or the grid - but there is only 1 ac input. If you need more power than the generator and the inverter can supply - using power assist, then you will need an external transfer switch to safely select either the generator input or the grid input - wiring this is a professional job.

Have as look at your maximum power demand, and see if you can't size the inverter and battery to suit this.

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big-blue answered ·

Hi and thank you very much for your fast response. Is this not possible with a multi or not possible at all. There is also a Quattro but I think also with this device this is not possible.

Thx

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Mike Dorsett avatar image
Mike Dorsett answered ·

The Quatro does have 2 x AC inputs, so the set up should be possible. I'm not sure if your requirement can be programed into the GX-control as I've never really used this unit.

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big-blue answered ·

Hi, i have read the ESS documentation. Maybe with the Quattro this is possible;

Here is the text from the manual:

Set the AC Input type to Generator when connected to a generator. The system will then enable generator-charging and correctly load the generator when running.

Note that we recommend wiring the Generator to AC-in 1, and the Grid to AC-in 2. The reason is that the Quattro will then prioritize the Generator over the Grid. That arrangement offers maximum flexibility (allowing forced generator intervention even when the grid is available) and maximises control.

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popnic avatar image popnic commented ·
@big_blue In the second statement in my opinion Victron says that if you connect the generator at AC-in1 and grid at AC-in2, if you start the generator the inverter will be connected to generator because it has higher priority. The AC-in2 - grid- will be disconnected.

To support my ideea, if you are looking in the Quattro manual, in the annex you can find system schematic. On both AC-in1 and AC-in2 inputs there are switches that connect to AC-in1 OR AC-in2 to the inverter AC side and AC-out1.

If both the both AC-in1 and AC-in2 are connected to the inverter then the generator will be connected also to the grid.

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shaneyake avatar image shaneyake popnic commented ·
The only way to really do this is to have 2 multiplus-II.

1 connected to grid
1 connected to generator
You can then move power from grid to battery when needed and have the other one completely off-grid. You can actually use both inverter outputs to each feed their own set of loads but outputs can not be joined.

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johnsmith avatar image johnsmith shaneyake commented ·

@shaneyake Is there a way to have a second Multiplus II just dedicated for generator charging of the battery bank? I know it can be done but the Cerbo GX won't allow 2 multiplus II to be connected at same time? I would like to have my Multiplus II 8k for the house feeding the CU and the second MPII 3K just setup to accept generator and charge the battery bank if the grid feed fails on AC in on the MPII 8K, so the batteries stay relatively charged from the MPII 3K/genny when the grid is down.

I know the Quattro can be used but I already have a spare MPII 3K.

cheers

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shaneyake avatar image shaneyake johnsmith commented ·
Yes, you can use a second Multiplus-II as a charger.


You don't need to have the second inverter connected to the GX at all but you can connect the second Multiplus to the GX via a USB to MK3 adapter. You will then get all the stats on the VRM Advanced page.


You can sent the input current limit on the GX but more more advanced control you will need to use NodeRed.

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