Victron in U.S with Autotranformer 120v->240v split phase

[ChrisG]

Yes, step up from 120v to 240v using Victron autotransformer with Quattro 5000 120v, please don't reply with EU 230v inverters and losing neutral topics.
Planning doing some work with a friend of mine and we're looking to back up some of his house loads, critical loads panel already in place. Really liking Victron but of course it's expensive. He has all 120v loads to backup except one low amperage 240v. We did the calculation based on his emporia energy meter install and even assuming a low 70% efficiency, one Quattro 5k will be enough as long as we can run it with split phase to the sub panel (already balanced 120v circuits in new panel). This is where the Victron autotransformer comes in (review the Victron diagram below).

Has anyone used this in the US? I know it's not UL etc. but seems like a solid solution over getting two MPII or Quattros for split phase setup. The additional benefit of Quattro is the dedicated generator input and auto switch between those if you need to charge your batteries if grid is not available.


I just have to say overall Victron is some amazing stuff and I'm just testing some used simple equipment on my own: Phoenix inverter, mmpt controller, smart shunt all working together and communicating, I have a mini 1200w 120v system of my own that is super impressive, specifically the idle consumption. Using Pi4 with Venus OS and the Victron Vrm. This stuff is quite amazing.

 

[RCinFLA]

Victron is well engineered and one of the few autotransformers that have safety features.

Issue with feeding 120vac loads with a 240vac to 120vac autotransformers is knowing when there is too much imbalanced 120vac load on autotransformer causing it to overheat.

To make matters worse, many manufacturers rate their autotransformer with no more than 50% 120vac load imbalance. Advertised '5kVA' autotransformers are really 2.5 kVA rated autotransformers. With 5kVA unbalanced 120vac load, these 2.5 kVA autotransformers will get over 100 degs C in less than 25-30 minutes.

Victron checks autotransformer heating and has a controller with solenoid tripped 240vac breaker from inverter 240vac to cut inverter's power if transformer overheats.

 

[ChrisG]

Victron is well engineered and one of the few autotransformers that have safety features.

Issue with feeding 120vac loads with a 240vac to 120vac autotransformers is knowing when there is too much imbalanced 120vac load on autotransformer causing it to overheat.

To make matters worse, many manufacturers rate their autotransformer with no more than 50% 120vac load imbalance. Advertised '5kVA' autotransformers are really 2.5 kVA rated autotransformers. With 5kVA unbalanced 120vac load, these 2.5 kVA autotransformers will get over 100 degs C in less than 25-30 minutes.

Victron checks autotransformer heating and has a controller with solenoid tripped 240vac breaker from inverter 240vac to cut inverter's power if transformer overheats.

@RCinFLA The loads will be balanced on the 120v sides. Example, one leg will have indoor fridge, another leg will have garage fridge, same balance with a few light and outlet circuits. Should be fine, including the 240v circuit. One use case he brought up was microwave but I feel that wounds put the AT pretty far out of balance.

So you feel this is an OK solution, obviously taking the balance into consideration? This will be for always on backup in the event the grid goes down.

 

[Rocketman]

Here is an idea that I don’t know if it’s ok - but it makes sense to me.

Instead of trying to balance the 120v ioads, could you have only the 240v loads running off the autoformer? All the 120v loads (including the autoformer input) are ran off a 120v panel.

This would probably make sense if the wiring was not already done - but not work out since the wiring is already in place.

 

[ChrisG]

Here is an idea that I don’t know if it’s ok - but it makes sense to me.

Instead of trying to balance the 120v ioads, could you have only the 240v loads running off the autoformer? All the 120v loads (including the autoformer input) are ran off a 120v panel.

This would probably make sense if the wiring was not already done - but not work out since the wiring is already in place.

The Quattro does have two outputs but one is only working if there is AC In. Not going to work in this situation for backup. Since I’m not worried about the balance he’s got setup thinking this will be a cost effective build with quality product. Just want to keep it simple.

Hoping @sunshine_eggo will chime in here on the overall thread. I think he's Victron ninja.

 

[ChrisG]

Well I researched all I could and see no issue using the Victron Autotransformer for step up from a 120v Quattro or any other 120v inverter to 120/240 split phase using the diagram above from their manual. In theory, if I have a 5k 120v Quattro wired into the Autotransformer (pass through or inverting) I can get 2.5kva 120v on each leg or 5kva 240v across both legs at full capacity and have the original neutral, not derived from AT.

Seems like a perfect solution compared to what others have done with 240v inverters and using a solar edge or Growatt autotransformer to make 120 with a AT derived neutral.

 

[740GLE]

so what’s the cost savings running the Auto xfrmr and one 5k Multiplus vs say two 3k Multiplus units?

Like $1000 bucks cheaper?

 

[ChrisG]

so what’s the cost savings running the Auto xfrmr and one 5k Multiplus vs say two 3k Multiplus units?

Like $1000 bucks cheaper?

I’d say about that. The issue he has is 1)limited wall space and 2) only one open circuit in main service panel (long story even after putting in critical loads panel). Agree two MPII would be the best solution.

 

[Jennifer]

Agree two MPII would be the best solution.

Just out of curiosity, why do you feel that 2 Multiplus's would be better than a Quattro with transformer? The balance per leg concern that was mentioned, redundancy should one fail?

Another good resource is the Victron Community Page:

Search - About 10000 Results Found - Victron Community

community.victronenergy.com

You shot down the native 230 option pretty quickly but it has some advantages, see this post from the above link (the first option he said that could not supply full output was a single 120VAC inverter with transformer like you're considering):



Jen

 

[Jack Rabbit Off Grid]

So you basically building a Victron into a Magnum PAE?

 

[ChrisG]

Just out of curiosity, why do you feel that 2 Multiplus's would be better than a Quattro with transformer? The balance per leg concern that was mentioned, redundancy should one fail?

Another good resource is the Victron Community Page:

Search - About 10000 Results Found - Victron Community

community.victronenergy.com

You shot down the native 230 option pretty quickly but it has some advantages, see this post from the above link (the first option he said that could not supply full output was a single 120VAC inverter with transformer like you're considering):

View attachment 134912

Jen

@Jennifer The 2 MPIIs for overall balance and possible redundancy for 120v but it just adds complexity.

I shot down the 240v version quickly at first but now understand the Victron AT is much more advanced compared to solar edge that others were using, specifically how it gets wired up BETWEEN inverter and panel. Those Victron links are making me rethink.

 

[ChrisG]

So you basically building a Victron into a Magnum PAE?

@Jack Rabbit Off Grid
We considered the Magnum and Schneider which are basically 240v with built in AT. Magnum I heard are solid, jut haven’t researched enough. The Schneider SW or XW I feel I’d be using my free time to help my friend out too often in it rather then kicking back having some beers.

 

[740GLE]

Soon as you see the blue light, every possible solution/system build look blue ?

 

[Jack Rabbit Off Grid]

@Jack Rabbit Off Grid
We considered the Magnum and Schneider which are basically 240v with built in AT. Magnum I heard are solid, jut haven’t researched enough. The Schneider SW or XW I feel I’d be using my free time to help my friend out too often in it rather then kicking back having some beers.

Magnum moved their assembly to Mexico. They are just now starting to ship new products into the US. I too wanted Victron also but didn’t want to deal with two inverters. I did end up going Magnum with Victron controllers.

 

[ChrisG]

Magnum moved their assembly to Mexico. They are just now starting to ship new products into the US. I too wanted Victron also but didn’t want to deal with two inverters. I did end up going Magnum with Victron controllers.

@Jack Rabbit Off Grid ,
If you don’t mind me asking, why Magnum over other like Schneider, Sol-ark, etc?

 

[Jennifer]

Duplicate Post, Delete-able.

 

[Jennifer]

I shot down the 240v version quickly at first but now understand the Victron AT is much more advanced compared to solar edge that others were using, specifically how it gets wired up BETWEEN inverter and panel. Those Victron links are making me rethink.

Yes, but limiting on the neutral as well.... spend some time reading on the Victron community pages before you make a decision. One person I know had their own transformer made for a homebrew version of the AT and it didn't have those limitations, I'll see if I can find you a link to some info.... below is a link to pics of the transformer, he uses it to balance the output of his Onan to feed dual 15KW Quattro's. The added benefit of having your own transformer built is you get to have the output legs configured how you need like he did.

Here's his write up about the problem and the solution:

Solar – Our Generator Gets Some Love – Granitepath

www.granitepath.com

(From his picture)
You may notice that the primary winding is 110v with the output being 240v/120v/120v. We did this because many of the RV parks we visit have low voltage. (no need for a Hughes Autoformer)

You can find pics of the transformer about 1/2 way down this page:

Our Solar Installation, Prior to March 2022 – Granitepath

www.granitepath.com

Here's his current system:

Solar Upgrades 2022 – Granitepath

www.granitepath.com

And his VRM portal:

Power System Status – Granitepath

www.granitepath.com

 

[Jack Rabbit Off Grid]

@Jack Rabbit Off Grid ,
If you don’t mind me asking, why Magnum over other like Schneider, Sol-ark, etc?

I had a 24v model that was 15 years old that I never had a problem with and knew how to operate it. Got the new one broken day one and have had nothing but problems getting it repaired. It’s been close to a year now.

 

[ChrisG]

Yes, but limiting on the neutral as well.... spend some time reading on the Victron community pages before you make a decision. One person I know had their own transformer made for a homebrew version of the AT and it didn't have those limitations, I'll see if I can find you a link to some info.... below is a link to pics of the transformer, he uses it to balance the output of his Onan to feed dual 15KW Quattro's. The added benefit of having your own transformer built is you get to have the output legs configured how you need like he did.

Here's his write up about the problem and the solution:

Solar – Our Generator Gets Some Love – Granitepath

www.granitepath.com

(From his picture)
You may notice that the primary winding is 110v with the output being 240v/120v/120v. We did this because many of the RV parks we visit have low voltage. (no need for a Hughes Autoformer)

You can find pics of the transformer about 1/2 way down this page:

Our Solar Installation, Prior to March 2022 – Granitepath

www.granitepath.com

Here's his current system:

Solar Upgrades 2022 – Granitepath

www.granitepath.com

And his VRM portal:

Power System Status – Granitepath

www.granitepath.com

@Jennifer Thanks for all the info, amazing the size of the transformer compared to a dollar bill on the build pictures.

Since this is only for critical load backup in his house (solar later) with that one 240v circuit and a few lights and outlets (indoor and garage refrigerators), I don't see a 28A neutral being a limitation but will stunt his future growth. Rethinking this now but the BLUE keeps drawing us both in with VRM and simplicity. If we do go Victron, think we will still do the 120v version. This will allow him to buy another Quattro in the future and run it in split phase and remove the AT for growth.

 

[740GLE]

That’s my plan, I have no 240v load needs at the moment so a single 3k Multiplus will suit my small loads if or when I need more headroom or 240v I’ll pick another one up.