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joshpoget asked

Which inverter is best for island setup?

I am building a system for my RV while building a home so it will be moved to the off-grid him in about a year. So far I have 2 12V 100 AH Battleborn Batteries, 8 - 335 Watt Solar Panels from Rich Solar and a Victron MPPT Tr VE. Can 150V 100 amp Solar Charge Controller. My RV has a 50 AMP service with 2 AC units, however, I have a generator to run those when needed. The RV came with a basic inverter to run the fridge and the outless unless run when plugged into shore power or a generator. I am wanting to add an inverter to run these from the solar panels directly while also charging the 2 batteries that can be used when the sun goes down for small loads. Is this something the Multiplus II can handle and it can be programmed to only deliver the max charge rate of the batteries or do I need something else. I want to avoid spending a lot on additional batteries. I can provide more details if needed, any help would be greatly appreciated. Thanks!

Multiplus-IIoffgridsolar
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seb71 avatar image seb71 commented ·

Do you plan to use those two batteries in parallel (so as a 12V battery) or in series (so as a 24V battery)? For large loads, higher battery voltage is better. And it would be best to go for a 48V system (48V battery).

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joshpoget avatar image joshpoget seb71 commented ·
I was thinking in series as 24 volt and I would have to get a dc converter for the 12 volt loads. I was also considering 48 volts, but I would have to buy 2 more batteries and not sure if 48 volt is ok on an RV?
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seb71 avatar image seb71 joshpoget commented ·
It sounded like the plan is to move this system in the new house, after the house is built.
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joshpoget avatar image joshpoget seb71 commented ·
Yes, after a year or so I am hoping to use most of the components for the house. That is when I would buy something like 48 volt server rack batteries that are 5000+ watts.
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seb71 avatar image seb71 joshpoget commented ·

Maybe you know, but just in case:

If you buy a 24V inverter now, you won't be able to use it with a 48V battery later (unlike the 150/100 MPPT charge controller).

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joshpoget avatar image joshpoget seb71 commented ·
So it makes more sense to buy 2 more batteries and make it 48 volts and use a 48 volt inverter and 48 to 12 volt converter for the RV? It is safe and common to see 48 volts in an RV?
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seb71 avatar image seb71 joshpoget commented ·
Maybe keep the RV as it is and buy stuff only after you designed the house system. Size that for the expected needs.


For instance you might need a bigger battery than 100Ah/48V, so buying two more of your existing 100Ah/12V batteries might not be the best choice.


Not to mention that it is not desirable to put in series old batteries with new batteries; but it depends on how much usage the existing batteries had.


If you connect them in series, follow the manual. Most important thing is to fully charge each 12V battery separatelly, before connecting them in series. You can use the Victron MPPT charger for that.
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