Off Grid - Multiplus in parallel or split phase?

[JaVid]

I am off grid. I own two identical 24/3000/70 Victron Multiplus'. I have only been using one over the last year or so - hardly ever need more than 2500 watts and if I do for a little while, the overload feature seems to work fine. Currently, I use the AC1 for my everyday loads on one side of panel and I use AC2 to run my two 12K mini splits on other side of panel. AC2 is programmed to only be available for my first 75% SOC, so when my battery gets below 25% SOC, I only run everyday loads (and battery heater).

Now I want to install the other Multiplus - either in parallel or split phase because I want to heat more this winter and also because my one multi was overheating when it got above 100 degrees recently. I don't currently have any 240v loads. I do want to maintain my ability not to run down my battery with the mini splits - this isn't an issue in summer, just in the winter when I want to use as much electrical for heat as possible, but keep enough battery for critical loads and keeping batteries warm. I don't use my generator much to charge in winter - I used 10 gallons in EU2000 last year in December in Wisconsin.

So - anyone have any ideas how to accomplish my goals? It would seem like parallel is the obvious choice, but can I still run an assistant in parallel and will that result in unbalanced loads? Also, it seems like split phase is easier to set up/wire/and not worry about unbalanced load sharing, but not sure how to use the assistant features in such a set up to accomplish only using mini splits for heating when I am over 25% SOC?

Any thoughts/ideas from the smart folks out there?

 

[sunshine_eggo]

It doesn't matter how you parallel them. They behave as a single inverter... either a 6kVA 120V or a 6kVA 120/240V, but they must be programmed correctly.

Please refer to link #5 in my signature, particularly if you plan for 120VAC parallel. How you wire BOTH the AC and DC sides are critical for balancing loads between them. In split phase, it barely matters.

Make sure both inverters have the same firmware.

You will need to configure them identically with the exception of the ground relay toggle steps as follows:

Save the VEConfig settings file from your existing inverter.

Power off units.
Disconnect from GX
Connect a cable between the VE.Bus ports
Power on both units, existing inverter first
Connect MK3-USB to either spare inverter VE.Bus port.
Open VE.Bus System Configurator.
Configure->Get configuration (at any time, you can right click either unit shown and "Flash LEDs" to show which inverter is which)
Select L1x2 or L1/L2.
Drag and drop both inverters to L1 or one each to L1 and L2.
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".
Configure>Send configuration.
They will now be working as you intended - single phase or split phase.
Right click the existing inverter, left click "VEConfigure Multi"

Example (note that these are for Quattros, so there are two AC inputs. You will only have one):


This will invoke VEConfigure. Confirm all of your settings are present. If not, ensure you're on the right inverter (Flash LEDs). If your setting are not present on either inverter, load the previously saved configuration file and Target > send settings.
Close VEConfigure.
Right click the other inverter, left click "VEConfigure Multi"
Load the saved configuration file.
Click the inverter tab and UNcheck ground relay. This is the N-G bond and should only be active on ONE inverter. If you have an N-G bond in the panel or elsewhere in the system, then BOTH should be unselected.
Target > send settings.
Close VEConfig
Close VE.Bus System Configurator.

Note that I may have made some errors in the above, but the overall sequence is the same. I use VRM and remote file download/edit/upload remotely, so the conventions are different than when direct connected. My biggest uncertainty is when to send settings. With VRM, I simply edit the settings and close VEConfig, and then I'm asked to save the config. It saves it to the downloaded file. Same with exiting VE.Bus sysconfig, asked to save file. Then I upload the saved file via VRM.

If anyone with recent direct connect experience has any corrections, please let me know.

 

[JaVid]

It doesn't matter how you parallel them. They behave as a single inverter... either a 6kVA 120V or a 6kVA 120/240V, but they must be programmed correctly.

Please refer to link #5 in my signature, particularly if you plan for 120VAC parallel. How you wire BOTH the AC and DC sides are critical for balancing loads between them. In split phase, it barely matters.

@sunshine_eggo - Thank you so much for the great reply with all the helpful details and good reminder about neutral/ground bond and configuring for generator input. Really helpful stuff and really appreciated!

I know they both have to be on same firmware, but do they both need to have same settings? Could I configure them as split phase and have one phase go to daily loads side of panel and have the other phase go to my mini split side of panel? And could I also program the inverter that goes to mini splits to have a different low-voltage disconnect? I know voltage isn't perfect for SOC, but that is what I use to make sure mini splits don't run down my battery completely. If I could do this, it would be great since I would basically be able to keep the same set-up I currently have. I am not sure if one inverter hit LVD it would turn off the other one?

 

[sunshine_eggo]

@sunshine_eggo - Thank you so much for the great reply with all the helpful details and good reminder about neutral/ground bond and configuring for generator input. Really helpful stuff and really appreciated!

I know they both have to be on same firmware, but do they both need to have same settings?

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.

Could I configure them as split phase and have one phase go to daily loads side of panel and have the other phase go to my mini split side of panel? And could I also program the inverter that goes to mini splits to have a different low-voltage disconnect? I know voltage isn't perfect for SOC, but that is what I use to make sure mini splits don't run down my battery completely. If I could do this, it would be great since I would basically be able to keep the same set-up I currently have. I am not sure if one inverter hit LVD it would turn off the other one?

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.

 

[JaVid]

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.

This ^^^^^ is Genius! Awesome and creative way to solve this! Thank you so much!

I don't have a GX (yet) - I surely will get it sometime soonish. I do have a smartshunt so that's good to know. While SOC would be better than voltage trigger, voltage can be a rough trigger after watching the system work for a while.

Good to know that the inverters both need to be working or the other will quit as well.

Thanks again, sunshine_eggo! I will be busy getting this set up the next couple of weeks.

 

[sunshine_eggo]

This ^^^^^ is Genius! Awesome and creative way to solve this! Thank you so much!

I don't have a GX (yet) - I surely will get it sometime soonish. I do have a smartshunt so that's good to know. While SOC would be better than voltage trigger, voltage can be a rough trigger after watching the system work for a while.

Good to know that the inverters both need to be working or the other will quit as well.

Thanks again, sunshine_eggo! I will be busy getting this set up the next couple of weeks.

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.

 

[JaVid]

Thanks for the push with the GX - I already know I will enjoy it and also benefit from it in understanding my system. Just need to pull the trigger.

Thanks again and I will keep this thread updated as I make progress.

 

[Madcodger]

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

Ummm... Raspberry Pi running Venus OS?

 

[sunshine_eggo]

Ummm... Raspberry Pi running Venus OS?

RPi running Venus OS is a GX.

 

[Madcodger]

RPi running Venus OS is a GX.

... that doesn't cost $300 +.

I think many people, especially those not familiar with the Victron product line and support resources, could easily assume you meant the Cerbo GX, which is an excellent product but perhaps more than a person wants to spend until they're more "into" this addiction we all love. The RPi is a great alternative for those that don't need the full functionality of that fine device, but it's often overlooked. Victron has done an excellent thing by making Venus available for the RPi. Many just don't know about it.

 

[sunshine_eggo]

... that doesn't cost $300 +.

I think many people, especially those not familiar with the Victron product line and support resources, could easily assume you meant the Cerbo GX, which is an excellent product but perhaps more than a person wants to spend until they're more "into" this addiction we all love. The RPi is a great alternative for those that don't need the full functionality of that fine device, but it's often overlooked. Victron has done an excellent thing by making Venus available for the RPi. Many just don't know about it.

Until somewhat recently, RPi prices have been absurd if you can find them. At those prices, there was no benefit.

Cerbo GX and Cerbo-S GX are both under $300 if you don't need a touch screen, which you don't get with an RPi either.

 

[Madcodger]

Until somewhat recently, RPi prices have been absurd if you can find them.

That was called a pandemic-related supply shortage. Down to $79.99 with case and power supply on Amazon, as of a minute ago. I had a couple of 3B's and extra MicroSD cards laying around from past projects (not uncommon for many here who tinker with electronics and such) so it cost me nothing but the necessary cable. The Victron GX products are great and I may one day buy a CerboGX and touch screen. I just think many people could benefit from knowing that there's an alternative that isn't widely publicized. And, it gets you wound up, so, "Bonus!". ? But seriously, you always have a lot of good info, especially re: Victron equipment. Thanks for that. Hard to beat blue.

 

[Adam De Lay]

That was called a pandemic-related supply shortage. Down to $79.99 with case and power supply on Amazon, as of a minute ago.

Can you share the link? I found just the Pi for around $70, but the kits were over $100.

I've have both the Cerbo and the Pi. I think a big part of the appeal to some for the Cerbo standpoint is the convenience. It already has all the different ports for the various protocols, temperature sensors and relays. With the Pi, if you only have 1 or two devices you need to connect, you might be ok. If you have more then you have to get an external hub, plus any adapters needed for the specific protocols you have to use. You can make the Pi do just about everything the Cerbo can do, as long as you can program it to do so.

I think each device has a use case. Having the VenusOS manage your environment is the important thing.

 

[sunshine_eggo]

I wanted to play around with RPi/Venus OS. I haven't checked until this thread, but RPi either weren't available or were >150 for the bare unit. Even now, they are not as prolific as they were pre-chip shortage.

Factor in the learning curve and a greater level of user abilities, and the economics evaporate. If one is very comfortable and has a RPi laying around, 1000% - do it. If you're Joe Schmoe off the street, whose never heard of RPi before, it's probably not worth pursuing.

Also would like that $70 link...

 

[Madcodger]

Can you share the link? I found just the Pi for around $70, but the kits were over $100.

I've have both the Cerbo and the Pi. I think a big part of the appeal to some for the Cerbo standpoint is the convenience. It already has all the different ports for the various protocols, temperature sensors and relays. With the Pi, if you only have 1 or two devices you need to connect, you might be ok. If you have more then you have to get an external hub, plus any adapters needed for the specific protocols you have to use. You can make the Pi do just about everything the Cerbo can do, as long as you can program it to do so.

I think each device has a use case. Having the VenusOS manage your environment is the important thing.

https://www.amazon.com/sspa/click?ie=UTF8&spc=MTo5NDEwMzQxNTUyODA2MDk6MTY5MzY1MDYyMTpzcF9hdGY6MzAwMDI0ODA4NzgxMjAyOjowOjo&url=%2FVilros-Raspberry-Clear-Power-Supply%2Fdp%2FB07BDRD3LP%2Fref%3Dsr_1_2_sspa%3Fcrid%3D2QKOV4MIUVB6O%26keywords%3Draspberry%2Bpi%2B3b%26qid%3D1693650621%26sprefix%3Draspberry%2Bpi%2B3%252Caps%252C137%26sr%3D8-2-spons%26sp_csd%3Dd2lkZ2V0TmFtZT1zcF9hdGY%26psc%3D1

Looks like it's a 2018 model, but I'm using one from that era and it's great. Also, Venus OS seems to work much better/easier on a model 3 than the newer model 4 RPi, from what I'm seeing on some of the marine forums, where the RPi running Venus seems to be more common.

 

[Adam De Lay]

https://www.amazon.com/sspa/click?ie=UTF8&spc=MTo5NDEwMzQxNTUyODA2MDk6MTY5MzY1MDYyMTpzcF9hdGY6MzAwMDI0ODA4NzgxMjAyOjowOjo&url=%2FVilros-Raspberry-Clear-Power-Supply%2Fdp%2FB07BDRD3LP%2Fref%3Dsr_1_2_sspa%3Fcrid%3D2QKOV4MIUVB6O%26keywords%3Draspberry%2Bpi%2B3b%26qid%3D1693650621%26sprefix%3Draspberry%2Bpi%2B3%252Caps%252C137%26sr%3D8-2-spons%26sp_csd%3Dd2lkZ2V0TmFtZT1zcF9hdGY%26psc%3D1

Looks like it's a 2018 model, but I'm using one from that era and it's great. Also, Venus OS seems to work much better/easier on a model 3 than the newer model 4 RPi, from what I'm seeing on some of the marine forums, where the RPi running Venus seems to be more common.

Gotcha, thanks. I was looking for a 4 at that price.

I can say my current 3B+ hasn’t had any issues.

 

[Madcodger]

I can say my current 3B+ hasn’t had any issues.

The 4 takes a different version of Venus and doesn't seem to be as robust as the version that runs on a 3B/3B+. I've had it running on a 3B+ I had laying around for about 10 months now, rebooting maybe 4-5 times only because I was fiddling with the system (added a shunt, added a shelf in the solar closet, etc.). Has gone months of that without a hiccup and has never *needed* a reboot. As for a learning curve mentioned in the thread, it's not completely plug in and run but it's also not as if a person needs to learn to code, either. Mostly downloading and copying/pasting some stuff from a forum, and then that's it. Recognizes new equipment (e.g., the shunt) on its own. A great gateway device to the Cerbo for many people or a "does most of what you need" device for others, at a fraction of the price, which is my core point.

 

[sunshine_eggo]

Ordered.

I was hoping to get the large version on it for some more advanced stuff like node red. Don't know if the 1G version can handle that, but I'll run whatever it can just for gigglz

 

[Madcodger]

Ordered.

I was hoping to get the large version on it for some more advanced stuff like node red. Don't know if the 1G version can handle that, but I'll run whatever it can just for gigglz

Cool! I hope it can handle Node Red for you. I haven't used Node Red yet, but a number of people that use the Hubitat device (my favorite home automation controller) seem to get great use from it. It's on my "learn this over winter" list but so are sooo many other things. Please let me know how you like Venus on the RPi. It's not a Cerbo GX, but it sure has been handy.

 

[sunshine_eggo]

Cool! I hope it can handle Node Red for you. I haven't used Node Red yet, but a number of people that use the Hubitat device (my favorite home automation controller) seem to get great use from it. It's on my "learn this over winter" list but so are sooo many other things. Please let me know how you like Venus on the RPi. It's not a Cerbo GX, but it sure has been handy.

It is purely proof of concept. I'll eventually either get a second VE.Can MPPT or a RS450/200. If I get a VE.Can unit, I'll need to upgrade to Cerbo for the separate BMS-CAN (Batrium) and VE.CAN (daisy chained MPPT) ports. I don't think the RPi can support the two separate CAN paths, but I'll figure that out. If I can do it all on RPi, I might do that.