Which inverter do I need?

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JoshPoget

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May 26, 2022
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St George, Utah
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!
 

Ex-Calif

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8 X 335 panels = 2680W - That's a ton of power.
2680 /12 = 223 amps.

I have a 100 amp charger so at 12V you are basically losing over 100amps that's not usable.

With a solar array this large you probably want to run at like 48 volts but that's not compatible with a 12V RV system.

I don't understand why you want/need to run the solar without the batteries in the system - are you thinkng a switching type arrangement?

When things are set up properly the RV and the solar don't care that the batteries are connected. As long as you are producing more power than you consume the batteries will charge and should end up in float mode.
 

JoshPoget

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St George, Utah
The system will still have 2 batteries, I am just looking to use the power directly from the sun to power larger loads and to charge my Tesla. So instead of investing in 2 Mult-Plus II inverters and 6-8 more batteries (about $10K) that would run everything, I am trying to just get an inverter that will use the excess power from the panels and not charge the batteries over their 0.5C recommended rate. I was thinking about running 24 volts and then using a dc converter for the 12 volt loads but it seems this wouldn't be necessary if I only charge 2 batteries and use the rest of the power directly?
 

Ex-Calif

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I am not a total expert on off grid solar but here is a representative sample of an off grid system that relies on the AC output from a solar inverter.

Where the house icon is you would have to have a suitable Tesla charger.

You may also need a little


off grid.JPG
 

Ex-Calif

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No - The solar inverter takes the solar panel DC voltage and converts it to AC voltage. You can see that everything to the right of the solar inverter is running on AC power.

Until you reach the RV charger/inverter which converts the AC to 12V DC that the RV can use.
 

solarman

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Feb 8, 2018
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Texas
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!

way too much wattage for a 12volt system.

what you are looking for here is known as "hybrid inverter charger with mppt"

we use these for both on and off grid.

typical units have
1. MPPT to control panels
2. Charger to charge batteries
3. Grid input to supply loads and also charge
4. inverter to provide power in the event of grid failure
5. 120 or 240V split phase outputs ( useful for 50A RV )

they may be programmed for off grid and supply power directly from panels or to/from batteries as required. plug a generator into the grid side and you can supply and charge at the same time.

most if not all are 48 volts as that's the standard for off grid.
also they don't come in small wattages, 4000 W and up is the norm
price starts around $1200 to $1500 and up for the small ones.

basically you plug everything into it, panels,batteries,generator and it will supply power to your loads
from any of those sources and can be programmed to charge when you have a surplus.

when programmed for solar priority, the panels power your loads and charge if you have a surplus, else power is drawn from battery, as will happen on partial cloudy days.
 
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touk

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Oct 19, 2021
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ontario canada
not sure if you are Touk?? I am Touk and seem to have become lost somehow. Not good with computers as you might suspect. Just need to see what has happened.
 

JayArr

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Jun 13, 2020
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Location
Mission British Columbia Canada
Take a look at the EX series by Xantrex.

I've got EX4000s in my shop right now that are 48V but have a 12VDC echo circuit on them. What his means is that your solar and battery bank can all be 48V and the inverter will not only make 120VAC from it, it will also make 12VDC from it to run the 12V systems in your RV (water pump, lights, fans, appliance circuit boards)

It's a great solution for the application that wants a high power solar/battery system but still needs to keep 12V lights on. It includes an 80A/48VDC charger for when you're on genny or shore power, 4000Watts of AC at 120VAC in a true sine wave coutput and 60A of 12VDC for the rig.
 
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