Off Grid - Multiplus in parallel or split phase?

[qcx1923]

If you plan to charge with 120V AC input on only a single inverter, UNcheck "switch as group". If you plan to feed both with 120VAC or both with split phase, then you do not need to uncheck "switch as group".

Unfortunately, this does not seem to work completely. I connected my 2x split-phase Multiplus-II 5k both to the same phase 120V input, but they would not charge when "Switch as a Group" was turned On. When turned Off, only the L1 MP would charge.

I really wanted this to work. I want to be able to switch from a 120V generator to a 120/240V generator with only a cable change.

 

[sunshine_eggo]

Unfortunately, this does not seem to work completely. I connected my 2x split-phase Multiplus-II 5k both to the same phase 120V input, but they would not charge when "Switch as a Group" was turned On. When turned Off, only the L1 MP would charge.

I really wanted this to work. I want to be able to switch from a 120V generator to a 120/240V generator with only a cable change.

It's working exactly as it should. You want something that's electrically impossible.

The inverters MUST be in phase with the incoming AC to pass through and charge. if they are in split phase, they can't accept the same single phase input on both, but EITHER can accept 120VAC individually while the other is not fed with AC in.

With switch as group off, AC input must be 120V to EITHER L1 or L2 - NEVER BOTH or 120/240V split phase to both.

The only way you can use the same 120VAC on both inputs is to reconfigure them for parallel 120V operation.

 

[sunshine_eggo]

$70 RPI 3 kit...

Whelp... good news and bad news.

Good:
Using a 128G MicroSD card (what I had laying about)... plenty of room for large w/Node Red enabled. 42GB free space remaining.
Relatively easy to setup.

Bad:
Need another $30 for a 2 channel CAN hat to allow VE.CAN bus communications for BMS and/or VE.Can MPPT. Not entirely clear if I can replicate the Cerbo BMS-CAN and VE.CAN functions. That puts me over $100, and a LOT of time invested.

Where I really see value is if you wanted a second smaller isolated system. In my case, I'm contemplating a separate system for a 12V pump. A small MPPT would do the trick... another $217 for a Cerbo-S would be really hard to justify, but a little RPi for monitoring via VRM sounds pretty luscious.

 

[rodrick]

Yes. As per above, they will (and must) behave as a single inverter. Both inverters expect the other to be there behaving identically to itself. If one inverter hits low DC shutdown, the other inverter will shutdown as well. If you simply unplug the VE.Bus cable between them, they will both shutdown. Hopefully, that addresses all of your following questions.



You can still keep the same setup you have, i.e., AC2 out can be configured to shutoff. Additionally, if you have a GX and a BMV/Smartshunt, I'm 99.9% certain you can program the criteria based on SoC. I've personally used assistants to trigger and terminate AC charging from grid based on SoC and the general flag. Should be able to do the same with AC out 2. The benefit of using SoC means you don't have to deal with voltage drop due to loads, which can trigger above the intended SoC.

If you did split phase, you could use the L2 inverter AC out 2 only - without connecting AC out 1, thus you would get the desired behavior, i.e, L1 inverter AC out 1 to L1 leg on panel, L2 inverter AC out 2 to L2 leg on panel. L2 leg shuts off based on your current criteria. If you wanted the L2 inverter to still power some loads, you could setup a separate panel.

How do you use just one multiplus ( 24/3000/70) when 2 are paralleled for 120 if only one is on you get a error code with my mpp units I can turn on either one, master or slave and they will work and with one running I can turn on the other and they sync up and share the load no restart needed

 

[sunshine_eggo]

How do you use just one multiplus ( 24/3000/70) when 2 are paralleled for 120 if only one is on you get a error code with my mpp units I can turn on either one, master or slave and they will work and with one running I can turn on the other and they sync up and share the load no restart needed

You reconfigure it to run in single mode.

 

[rodrick]

You reconfigure it to run in single mode.

So my cheap mpp 2424mds which I paid less for 2 of them than 1 of my victron multiplus tier 1 top of the line unit do it automatically and with the victron I have to reconfigure, well hell that’s like having to pull start your Mercedes Benz for the price the mpp units are pretty good deal even with the double standby consumption rate

 

[sunshine_eggo]

So my cheap mpp 2424mds which I paid less for 2 of them than 1 of my victron multiplus tier 1 top of the line unit do it automatically and with the victron I have to reconfigure, well hell that’s like having to pull start your Mercedes Benz for the price the mpp units are pretty good deal even with the double standby consumption rate

Have you actually verified this function with an actual failure?

Victrons are effectively a single inverter once configured. Part of Victron's reliability comes from their restrictive requirements.

Tell me how well your MPPs handle dirty generator power.
Tell me how well your MPPs boost incoming AC to provide additional power to prevent overloading the generator or weak AC input.
Tell me how well your MPPs log detailed system information and allow remote access and troubleshooting by your dealer.
Tell me how many new features have been added in the last six months.
Tell me where you can go to engage the development team and ask for specific improvements.
Tell me where you can go to get free video training on system installation and configuration.

 

[rodrick]

Yes I have cycled both mpp units while running and they go into single mode automatically and when one gets turned back on it goes back to load sharing I just think that’s a pretty cool feature for a cheap Chinese import maybe victron could copy it because it really convenient just flipping a switch to drop a inverter of line when not needed to conserve power

 

[sunshine_eggo]

Yes I have cycled both mpp units while running and they go into single mode automatically and when one gets turned back on it goes back to load sharing I just think that’s a pretty cool feature for a cheap Chinese import maybe victron could copy it because it really convenient just flipping a switch to drop a inverter of line when not needed to conserve power

Power cycling isn't a failure.

Funny thing that you're power cycling one to conserve power... where Victron units consume substantially less power. My 10kW of Quattros burns about 56W idle.

 

[rodrick]

Power cycling isn't a failure.

Funny thing that you're power cycling one to conserve power... where Victron units consume substantially less power. My 10kW of Quattros burns about 56W idle.

True the victron units are half of the mpp consumption, that and their quality is why I bought them being this system is totally offgrid nearest grid is 10 mile away I just thought being able to go down to one inverter when loads are light to conserve should be easier than doing a reconfiguring of the system I even have a third system with a 1.5 kw inverter that only draws 7 watts in standby if I have to really conserve I can switch to if desperate times present them selves with that said I would’ve thought that victron with all the bells and whistles they have would do it automatically like the mpp units do

 

[JaVid]

Get a GX now. I drug my feet on getting my CCGX up and running for a few months (wish I'd sprung for a Cerbo at the time). I felt so stupid having waited for so long due to the additional features and remote monitoring/controls. It absolutely transformed it. It gives me daily security and joy. Yes. I'm weird.

Without a GX, there's no way to pass the smartshunt SoC to the inverter, so you can't do it based on SoC.

Agree that you can do it with voltage, but as you've indicated, it takes observation and some trial and error.

Keep us posted. If you have any questions, just post back to this thread.

I got the GX-S and it just came today. Cant wait to get it hooked up! Your post made me pull the trigger - Thanks again for all your help.