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bla32 asked

Best victron device for AC coupled storage / UPS

Good Evening,


I'm looking to set up my grid tie system with some battery storage and looking on the best victron device to do it based on my specifics. I think the multiplus would be suitable?

I run an existing 8KW 22V systen based on a 6S li-ion batteries, which runs a UPS and some DC loads.

As I understand, I can use Victron DVCC system to manually change the charge voltage to accommodate for these batteries. The charge voltage should be limited to 24.6V (4.1v/cell) instead of the more usual 28V+.

I would also like the inverter to be able to switch off when battery voltage drops below 19V and only restart once above 21V. I'm unsure whenever the inverter can be programmed as such or if I need external circuitry.

Presently, I have a grid tie setup with a 3.6KVA inverter and a separate charger and UPS. Ideally I would like to use the victron to replace the existing UPS. The goal is to make the battery AC coupled so it's charged on any surplus export with the inverter boosting the AC output in periods of demand / night.

My needs are for the inverter to offer about 1KW of autonomous power as a UPS, but I am unsure about it's behaviour when household mains is available. Will it assist the grid, providing the available grid capacity + the inverter capacity? Or will I still be limited to the rated inverter output, therefore having to choose a 3+KW model? I understand during a grid outage available power = inverter max power. My query is when the grid is available.

I am also not sure on how the victron multiplus works - Can it inject power on the grid to make up for the house usage? Or is it limited to supplying loads on its output, therefore not drawing from the grid?

Thanks!

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Duivert NL answered ·

Multiplus 2 can do all of that, support grid, run from battery and or pv (day or night) backup when grid fails, take a look at the manual or datasheet for more info

In your case i think its a bit difficult with your battery voltage 22v is low, 24v model specs are 19-33v input voltage, maybe someone else or a dealer knows more on that

Best is to contact your local victron dealer for support on setting up your system

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bla32 avatar image bla32 commented ·

Thanks.

Quite honestly I was trying to avoid the 'sales guys' as I will be buying on a country I don't speak the local language.

The battery will stay within the 19V+ range, so not too worried about that.

The multiplus II seems to be ideal, but the smallest I can find is 3KVA. The older multiplus range goes a bit further down into the KW range, but the information I find is confusing on whenever it can back feed or it will simply assist a load on it's output.

For Either type it also seems I need an external current sensor and some kind of interface for the VE.Bus configurations. Here I'm also not sure as it seems some have built in Bluetooth allowing parameter change through an app.


If anyone has one and can share experiences, that would be great!

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Duivert NL avatar image Duivert NL commented ·

yes, the smallest multiplus 2 is 3kw, and then a GX version so you dont need a separate cerbo, for a small setup there is no need for a gridmeter/external current sensor but that also depends on how its connected to grid


you dont need an ve bus interface for setup, single multiplus can be setup thru local/VRM remote console and or victron direct app


if your batterie bms is supported it can be connected on can bus of multi gx, or you could use a ve direct shunt

because of all the options en differences in use and setup, its community policy to let system design done by a local dealer, you could also sign up for free victron professional account and follow online trianing courses, victron has a lot f documentation for self study:


https://www.victronenergy.com/media/pg/Energy_Storage_System/en/index-en.html

https://www.victronenergy.com/upload/documents/The_Wiring_Unlimited_book/43562-Wiring_Unlimited-pdf-en.pdf

https://www.victronenergy.com/live/battery_compatibility:start

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