48v Multiplus-II: UL 1741 ?

[fafrd]

I am going to stop responding in regards to the Victron roadmap because I don't want to speak out of line or have words put into my mouth.

I heard back directly from Victron on my question regarding a UL1741-listed version of the Multiplus II 2x120V and here is the response:

‘This depends on demands in the market’

The Multiplus II 2x120V holds a unique position in the <3kW ESS market and I just hope as the ESS market in California adjusts to the new reality presented by NEM 3.0 that you and Victron’s other vendors here in the US can make that opportunity clear to them.

 

[ChrisG]

I heard back directly from Victron on my question regarding a UL1741-listed version of the Multiplus II 2x120V and here is the response:

‘This depends on demands in the market’

The Multiplus II 2x120V holds a unique position in the <3kW ESS market and I just hope as the ESS market in California adjusts to the new reality presented by NEM 3.0 that you and Victron’s other vendors here in the US can make that opportunity clear to them.

So this version of the MPII x2 can pass through split phase from source (grid or generator) but can’t make split phase inverter power?

 

[cs1234]

So this version of the MPII x2 can pass through split phase from source (grid or generator) but can’t make split phase inverter power?

Correct, at least with a single unit. When it loses external spit phase, it converts over to a single leg of 120v and supplies it to both legs downstream. 240v devices simply stop working (no damage or anything supposedly) and 120v devices are happy as can be.

 

[zanydroid]

. (redundant)

 

[sunshine_eggo]

So this version of the MPII x2 can pass through split phase from source (grid or generator) but can’t make split phase inverter power?

Correct. No Victron inverter is split phase capable. You either run two in parallel, or you get an EU unit set for 240V/60Hz and their Autotransformer.

 

[zanydroid]

I would surmise that the parallel 120/240V config is appropriately listed for the US (for the listed ones, that have 120/240V config included in the manual, thus has been vetted by NRTL unless otherwise clarified) - so in that sense it is split-phase capable.

 

[fafrd]

So this version of the MPII x2 can pass through split phase from source (grid or generator) but can’t make split phase inverter power?

Correct. The advantage of the Multiplus II 2x120V is that you can supply a split-phase critical loads panel with balanced 120VAC loads (including non-critical 240VAC loads) while being able to both charge a battery as well as fast loads on one phase.

If you need full full split-phase 240/120VAC, you’ll need 2 120VAC Multiplus inverters, so the Multiplus II 2x120V doesn’t offer any real advantage.

But if you only want to spend half as much to offset load and time shift a single leg with no more than 2400W (load-shaving), as well as to provide backup power to 120VAC critical loads, there is no offering currently that competes against the Multiplus II 2x120V.

 

[fafrd]

I would surmise that the parallel 120/240V config is appropriately listed for the US (for the listed ones, that have 120/240V config included in the manual, thus has been vetted by NRTL unless otherwise clarified) - so in that sense it is split-phase capable.

Correct. No single Victron inverter is split-phase capable, but a pair of them are.

 

[ChrisG]

Correct. No Victron inverter is split phase capable. You either run two in parallel, or you get an EU unit set for 240V/60Hz and their Autotransformer.

@sunshine_eggo
Been going back and forth in this decision. So for the EU 230v version in the US, pass L1, L2 and ground from main panel to Inveter, do not connect neutral. Connect inverter Ground, L1 and L2 to the Auto Transformer. The Auto Transformer would then make split phase and become the G-N bond for the subpanel. Is that accurate and safe?

Not worried about the max 28A neutral on AT. Microwave and coffee pot on two separate sides of the panel

 

[sunshine_eggo]

@sunshine_eggo
Been going back and forth in this decision. So for the EU 230v version in the US, pass L1, L2 and ground from main panel to Inveter, do not connect neutral. Connect Ground, L1 and L2 to the Auto Transformer. The Auto Transformer would then make split phase and become the G-N bond for the subpanel. Is that accurate and safe?

For a Quattro in RV, but same for MP except you'll only have one AC in.

https://www.victronenergy.com/upload/documents/AT-1-split-phase-240V-to-120-240V-with-Quattro-240V.pdf

Note the wording:

"grounding relay of autotransformer is in use. Grounding relay of Quattro must be disabled"

and top right:

 

[ChrisG]

For a Quattro in RV, but same for MP except you'll only have one AC in.

https://www.victronenergy.com/upload/documents/AT-1-split-phase-240V-to-120-240V-with-Quattro-240V.pdf

Note the wording:

"grounding relay of autotransformer is in use. Grounding relay of Quattro must be disabled"

and top right:

View attachment 137203

@sunshine_eggo
Sorry, should have been more clear. This is for a grid connected cabin. Not sure if that changes anything.

 

[zanydroid]

You probably don’t want a grounding relay active then. And use the N-G bond at the MSP. Unless you disconnect neutral from MSP when off grid for some reason. Not a normal situation unless you want to protect against all possible utility transformer issues.

 

[zanydroid]

What kind of control does victron have over how it reacts to getting/losing grid power? Can it be wired to remote grid presence sensor and transfer relay?

 

[ChrisG]

You probably don’t want a grounding relay active then. And use the N-G bond at the MSP. Unless you disconnect neutral from MSP when off grid for some reason. Not a normal situation unless you want to protect against all possible utility transformer issues.

But the neutral is not connected to the 230v EU inverter and created by the AT going to the sub panel. Only way I would see that working possibly is if the sub panel is also connected to main panel and only the hots are switched via an interlock. If that’s the case you would have grid neutral and ground bond from main panel to sub panel as well as the neutral and ungrounded bond from inverter/AT (don’t close the bond relays in inverter or AT). Would that work?

If that’s how it should work easy enough.

 

[zanydroid]

You can have both hot only and hot+ neutral transfers. I don’t know which one is right for what situation. If hot only and there is a neutral path back to MSP from critical loads then you have to disable the relays on the inverter and AT.

 

[ChrisG]

You can have both hot only and hot+ neutral transfers. I don’t know which one is right for what situation. If hot only and there is a neutral path back to MSP from critical loads then you have to disable the relays on the inverter and AT.

Apparently you have full control of what the ground/neutral bond relays do via the software setup in both Inverter and AT in pass through and inverter mode. Since you can control them seems no different than an interlock with a generator supplying its own neutral to a panel. Both neutrals connected, generator with floating ground since G-N bond is in main panel.

 

[zanydroid]

Since you can control them seems no different than an interlock with a generator supplying its own neutral to a panel.

Sure. The only difference I think is that the bond can be dynamically changed as needed vs manually installing or removing a N-G jumper in the generator.

 

[sunshine_eggo]

@sunshine_eggo
Sorry, should have been more clear. This is for a grid connected cabin. Not sure if that changes anything.

No. It doesn't. You simply need to adapt it for the cabin.

 

[ChrisG]

Sure. The only difference I think is that the bond can be dynamically changed as needed vs manually installing or removing a N-G jumper in the generator.

So I just found this bit of info from the VE config document. The “Warning:” is my concern:

10.3.1. Inverter output voltage
This is normally 120/230 Vac.
10.3.2. Ground Relay
Used to enable/disable the internal ground relay functionality. Connection between N and PE during inverter operation.
The ground relay is useful when an earth-leakage circuit-breaker is part of the installation. When the internal transfer switch is open (inverter mode) the Neutral of the inverter is connected to PE. When the transfer switch closes (AC input is transferred
to the output) the Neutral is first disconnected from PE. Warning: Disabling the ground relay on "120/240V" models (split phase models) will disconnect the L2 output from the inverter.

Doesn’t sound like we can disable it if connected to a sub panel that already has a G-N bond without impact to L2 if I’m reading this right.

https://www.victronenergy.com/upload/documents/VE.Bus_Configuration_Guide/VE_Bus_Configuration_guide-en.pdf

 

[fafrd]

So I just found this bit of info from the VE config document. The “Warning:” is my concern:

10.3.1. Inverter output voltage
This is normally 120/230 Vac.
10.3.2. Ground Relay
Used to enable/disable the internal ground relay functionality. Connection between N and PE during inverter operation.
The ground relay is useful when an earth-leakage circuit-breaker is part of the installation. When the internal transfer switch is open (inverter mode) the Neutral of the inverter is connected to PE. When the transfer switch closes (AC input is transferred
to the output) the Neutral is first disconnected from PE. Warning: Disabling the ground relay on "120/240V" models (split phase models) will disconnect the L2 output from the inverter.

Doesn’t sound like we can disable it if connected to a sub panel that already has a G-N bond.

https://www.victronenergy.com/upload/documents/VE.Bus_Configuration_Guide/VE_Bus_Configuration_guide-en.pdf

I really don’t understand why anyone would pursue the 230VAC Multiplus II + Autotransformer configuration for a grid-tied solution here in the US…

It’s not a UL-Listed solution and not one that Victron promotes for residential grid-tied installs here, so what is the motivation over a dual-Multiplus UL-Listed split-phase solution, cost-savings?