dwarden avatar image
dwarden asked

2 x MultiPlus-II 3000VA 48V in parallel vs MultiPlus-II 8000VA 48V

I have a SolarEdge 6kW grid-tied inverter (SE6000HD) with an oversized 9.3kW PV array at our home with a single phase supply. I would like to add battery storage that will allow the inverter as an essential load and thus keep the existing PV generating in a powercut.

The Victron/SolarEdge details show that the MultiPlus 48V is well suited to this and how it would be done ( However, Factor 1.0 means that I need 6000VA (plus sufficient battery capacity, which appears to be 19.2kWh). This leads me to the MultiPlus-II 8000VA, but this is quite a step up in price from the 3000VA and 5000VA units. The cost of 2 x 3000VA units is only two-thirds of the price of 1 x 8000VA unit.

Victron's specific instructions for parallel systems makes for a more complex installation ( However, provided these are followed, is there a good reason for going for the larger single unit at much greater cost over two parallel units that fit our sizing requirements? We may add some DC PV, either now or in the future, but I don't think we would need the extra capacity of the 8000VA unit (we are restricted to 6kW export).

Beyond a simpler install, the benefits I can currently see for the 8000VA are the 6.4kW output over 4.8kW (2 x 2.4kW for the pair of 3000VA units) and the 110A battery charge current over 70A (2 x 35A). I understand the former, but don't yet know how the latter would affect us in practice.

Having a pair would allow for some flexibility/redundancy (following some reconfiguration) in the event that one of the units needed to be repaired.

Thanks in advance for any assistance.

Multiplus-IImultiplus in parallel
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2 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

Having operated a smaller parallel system for several years, I don't see any issue with this approach. In complexity, it is only a little more wiring. In terms of redundancy, one unit could be reprogrammed to run the system while the other is replaced. If you want to move to dc charging, then it would be possible to limit the solar edge inverter by removing sone of the PV from it's input, and connecting the modules to an MPPT charger.

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groningen avatar image
groningen answered ·

@dwarden, good question. I am also in the process of doing something similar (2 x multi-plus ii setup_ DIY). Would like to know if someone ran into some "difficulty" or share their experience or even recommendations. As stated by @dwarden, obviously one unit is more simplistic, but sometimes other factors does lean towards two small units running in parallel.

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