48v Split Phase Stackable Inverter options?

MDW

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I know Growatt has a 5kw that with a transformer can do split phase but what do you think about the transformer idea?
I'm not sure what my complete load is going to be yet so expandable system would be great.
Does a 48V split phase stackable exist? Something in the 5-6kw range?
 

MurphyGuy

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Most decent 48volt split phase battery inverters have an option to stack them. Not sure about the Chinese junk being sold, but all the names like Outback, SMA, Victron, etc can all do it.
 

MDW

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Thank you for taking the time to respond.
I wasn't aware that.
I will look harder
 

DThames

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Unless someone has studied series and parallel circuits the auto-transormer to create the neutral not easy to understand. It would be worth your time to study and try to understand it. I will try to explain but I am not sure it will be clear.

Suppose you have a 2000w, 240v load on the output. That is easy to understand. Now, connect the auto-tranformer to the same 240v output. The transformer is acting a lot like a high impedance load (almost no load) and is just sitting there with its neutral ready in cause you have a 120v load.

Imagine the transformer is rated at for 20 amps of imbalance. I am not sure how they are rated, not important at this point. So you connect a 5 amp load on one leg (L1) of your transformer, to the neutral. The 5 amp load is in parallel with one half of the transformer and in series with the other half. Now connect a 4 amp load to L2 and the transformer neutral. That 4 amp load is parallel to the other half of the transformer and in series with the other half that is parallel to the 5 amp load. So if you ignore the transformer (for a second....because it is almost no load by itself) you see your 4 amp load and your 5 amp load are in series, connected to 240v. This the way split phase off the grid works as well. With 5 amps on one leg in series with 4 amps on the other leg, the voltage would not be 120v and 120v but the transformer winding is much larger in terms of what current it can carry and acts as a much larger voltage divider, holding the neutral very close to the middle of 240v. If you load one leg much more than the other leg, you make the transformer do more work. You get more losses in this case. But if you can keep the load on the two legs fairly close to balanced, the load can be pretty large, way larger than the transformer rating because the rating is based on imbalance and the amount of work to keep the neutral in the center. So one transformer in a fairly large well balanced split phase system is all you need. This video might help understand a bit but it does not go into the circuit details. You can draw it out and study it. Once you see how it works there will be an "aw-ha".
 
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houseofancients

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mpp solar's stack up to 6
deye/sol-ark/sunsunk stack up to 6
growatt stack up to 6
victron stack up to , i believe, 8
 

DThames

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Growatt has a stackable split phase?
I will look into the others, thank you
The Growatt 3000, takes two to make "split phase" can also be stacked. You can even run 2 on one leg and 1 on the other leg if you like. I have a pair of the 3000w to make 240v.

You can stack that 5000w 240v model as well. And again, if you need 120v one of those transformers is needed, but not one per inverter.
 

MDW

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The Growatt 3000, takes two to make "split phase" can also be stacked. You can even run 2 on one leg and 1 on the other leg if you like. I have a pair of the 3000w to make 240v.

You can stack that 5000w 240v model as well. And again, if you need 120v one of those transformers is needed, but not one per inverter.
I'm not sure how I feel about the transformer to create the neutral, seems like another failure point with very bad consequences. I'm may be over thinking it.
 

Tecnodave

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The Magnum Energy MS4048PAE is natively 120/240 volt split phase and can be stacked. The main transformer in these units is an autotransformer and does not need an external transformer.

Note that an external autotransformer does load down the inverter/charger with an external inductive load which is not well tolerated by high frequency inverters.
 

MDW

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The Magnum Energy MS4048PAE is natively 120/240 volt split phase and can be stacked. The main transformer in these units is an autotransformer and does not need an external transformer.

Note that an external autotransformer does load down the inverter/charger with an external inductive load which is not well tolerated by high frequency inverters.
Thank you very much, this is the kind of info I have been needing.
I'm starting to think that I should go with a much larger inverter (12k) than I think I need so I don't have to worry about expansion
 

DThames

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I'm not sure how I feel about the transformer to create the neutral, seems like another failure point with very bad consequences. I'm may be over thinking it.
A lot of the lower cost "split phase" options requires 2 inverters which is also another failure point. I would not argue too much either way but if I where starting over I would be looking harder at the 240v output with the autotransformer.
 
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Porch

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A lot of the lower cost "split phase" options requires 2 inverters which is also another failure point. I would not argue too much either way but if I where starting over I would be looking harder at the 240v output with the autotransformer.

The Outback system uses 2 inverters for split phase 240v, but they have an auto transfer to balance the load. So one inverter can sleep while the other handle the light loads on both phases. The second one kicks on when there is heavy demand.

It's not automated in anyway, but in the case of an inverter failure, you can operate the system with just one inverter and still get 240v. So it adds a bit of redundancy.
 

Tecnodave

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The Outback system uses 2 inverters for split phase 240v, but they have an auto transfer to balance the load. So one inverter can sleep while the other handle the light loads on both phases. The second one kicks on when there is heavy demand.

It's not automated in anyway, but in the case of an inverter failure, you can operate the system with just one inverter and still get 240v. So it adds a bit of redundancy.
Correction....

Some Outback systems use 2 inverters for split phase, The larger ones are 120/240 in a single unit (RADIAN)
 
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