mixing quattro and multiplus-2 single phase

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farmeroz asked Feb 27, '24

mixing quattro and multiplus-2 single phase

OK, I have a system. Quattro 10k and a MPPT rs 450-100, 6kW solar with 20kWh victron smart batteries. Cerbo etc.

User would like to grid-tie.

This cannot be simply connected to grid via the Quattro-mk1. The alternatives seem to be:

1) Replace the 10kw Quattro with a 10kW Multiplus-ll.

More expensive and much rewiring needed to make space for bigger unit. Separate generator input is lost.

2) Add a smaller multiplus-ll (say 5kW) and grid tie this to grid off same battery array.

Cheaper, can be added in new convenient location, small amount of power may be lost at peak summer. This IS not worth much though.

The thing is, can you just add an extra multiplus-ll?

Multiplus-II grid quattro 10kva

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Answer 1 · 2024-02-27T13:36:43Z

Alexandra answered · Feb 27 at 01:36 PM

@Farmeroz

What exactly are you trying to accomplish here? Just connect legally to grid?

You can't connect the Quattro because it does not meet standards? Easier option may be to add a zeihel.

Having two inverters on one bank (not matching) is not supported officially. People do do it. The Cerbo is only designed to control one, so from that side it will be a dumb inverter. Or the quattro will be dumb depending on how you connect them to the Cerbo.

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Answer 2 · 2024-02-27T15:44:09Z

farmeroz answered · Feb 27 at 03:44 PM

Alexandra, thank you for your prompt reply.

The quattro is already installed and powering a UPS unit.

As you say it cannot be connected to the grid any sense, the zeihel looks like a bodge. Also I have seen posts suggesting it doesn't really meet UK specifications anyway.

1) Its very unclear to me how the control of charging is actually done in the victron system. The cerbo seems to claim that bms is from the quattro, yet the MPPT is clearly modulated, presumably via the cerbo.

2) An alternative may be to use a smartshunt to control battery charge with the four batteries connected through the shunt to the common 48V bus. Then the quattro would be a dumb inverter (switched on or off via the BMS relay on battery low as required) and the multiplus running smart to send power to the grid as required and the smartshunt controlling battery operation.

Hmm, quite interesting. Pity you can't get the Multi to pass mains through to the Quattro for power assist and still maintain the required double-isolation. Maybe?

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