Hi All

I am investigating implementing a Solar/Battery system in a 3 phase residential environment. I have no experience in this field. I see there are a few topics discussing this but I am still confused and hoping to get some clarity here, particularly wrt configuration. There is no 3 phase equipment. Most of the installers can't seem to answer my questions or I am not asking it properly or I must be completely confused and my questions make no sense! Please bear with me.

As I understand, the options are:

1. Use a 3 phase inverter.
2. Convert the DB to single phase and use a big enough single phase inverter.
3. Convert the DB to single phase and use 2 or more single phase inverters.
4. Use a single phase for the load which require solar/backup.
5. Leave the DB as 3 phase and use a single phase inverter per phase.

My questions are around how to connect the battery and PV in each scenario. 

Scenarios 1,2 and 4 are easy - there is only one inverter and the battery and PV input is clear.

Scenario 3 and 5 is a little more complex. 

In scenario3, if I use multiple inverters, is it possible to use 1 battery and 1 pv array for all the inverters. How do you connect this?

In scenario 5, If I use 3 single phase inverters ( one per phase ):

1. Is there a way to connect a single battery so that any/all of the inverters can draw from the battery bank simultaneously? In this case, which inverter charges the battery and can the charging of the other inverters be turned off ?
2. Is there a way to connect the PV input so that any/all of the inverters can draw from the PV array simultaneously?

Or, do I need 3 separate battery banks and 3 separate pv arrays ?

Any help would be appreciated. 

Thank you. 

 

1 hour ago, James1 said:

Is there a way to connect a single battery so that any/all of the inverters can draw from the battery bank simultaneously? In this case, which inverter charges the battery and can the charging of the other inverters be turned off ?
2. Is there a way to connect the PV input so that any/all of the inverters can draw from the PV array simultaneously?

Or, do I need 3 separate battery banks and 3 separate pv arrays ?

Yes,  as per Axpert inverters thats in fact the only way sharing works, that is a common battery bus. But you must setup the inverters to be either in parralel mode or 3 phase mode.

And in exactly the same manner will pv enegy be shared, that is thru the battery bus.  One inverter might think its charging the batteries with pv power, but instead another inverter is discharging that energy for its own use. Simple but magic way of sharing! 

Contact @Steve87for expert configuration options. He is excellent in this regard. 

Edited September 25, 20223 yr by BritishRacingGreen

@BritishRacingGreen Thank you for the response. It is very helpful. I appreciate it.

Hi @James1i can only talk intelligently on the Kodak/ Voltronics OEM way of 3 phase architecture. Other inverter manufacturers also have ways to achieve this with also good results. As @BritishRacingGreensays the Voltronics way of Parallel operations is very intriguing. You can parallel & stack to achieve a power requirement for up to 45kW in any configuration in Single or 3 phase. 

The fundamentals: 

Each single phase group must have the small red & black power sharing cables installed within that group.

So eg. Phase A will all share current equally etc. Phase B will have its own group of cables. Of course a single machine in each phase will not have current sharing cable because each machine will carry each phase current alone. 

The Machines will not output power in a 3 phase configuration until the settings in Menu option 28 is setup correctly. You tell each machine which phase it needs to synchronise to. Options are 3P1, 3P2 & 3P3. If you don't get this done right, the machines will not output power. 

The machines use available Solar power as required as is made available to each MPPT. The phases are obviously independent so phase can can draw up to the inverter limit on each phase

The beauty of the 3 phase Architecture comes with the Single Common battery bus. All Inverters must be paired to the same battery bus. It seems a pain & you must get your battery bus & cables lengths equal as explained in the Wiring unlimited document by Victron. The beauty is that the 3 phases are all apart & independent. But the battery bus can be getting charged by one machine & get discharged by another machine. So effectively the energy is common to each. So Phase A is in SBU mode & discharging at 20A DC & Phase B can be charging from Solar at 50A DC. The net result is a 30A DC charge into the batteries.

Its really amazing to watch & I must admit this is my favourite way to connect a Kodak / Voltronics. It's really really robust & you can stack as many in a phase as you like. So you can have 3 machines in Phase A & 1 machine as Phase B & 1 machine in Phase C.

 

Awesome, this is exactly what I wanted to know. Thank you so much @Steve87. One more question, and again excuse my ignorance, which Kodak axpert models support this.. the one with the round panel/lcd in front or older models as well ? I don't know models

2 hours ago, Steve87 said:

Hi @James1i can only talk intelligently on the Kodak/ Voltronics OEM way of 3 phase architecture. Other inverter manufacturers also have ways to achieve this with also good results. As @BritishRacingGreensays the Voltronics way of Parallel operations is very intriguing. You can parallel & stack to achieve a power requirement for up to 45kW in any configuration in Single or 3 phase. 

The fundamentals: 

Each single phase group must have the small red & black power sharing cables installed within that group.

So eg. Phase A will all share current equally etc. Phase B will have its own group of cables. Of course a single machine in each phase will not have current sharing cable because each machine will carry each phase current alone. 

The Machines will not output power in a 3 phase configuration until the settings in Menu option 28 is setup correctly. You tell each machine which phase it needs to synchronise to. Options are 3P1, 3P2 & 3P3. If you don't get this done right, the machines will not output power. 

The machines use available Solar power as required as is made available to each MPPT. The phases are obviously independent so phase can can draw up to the inverter limit on each phase

The beauty of the 3 phase Architecture comes with the Single Common battery bus. All Inverters must be paired to the same battery bus. It seems a pain & you must get your battery bus & cables lengths equal as explained in the Wiring unlimited document by Victron. The beauty is that the 3 phases are all apart & independent. But the battery bus can be getting charged by one machine & get discharged by another machine. So effectively the energy is common to each. So Phase A is in SBU mode & discharging at 20A DC & Phase B can be charging from Solar at 50A DC. The net result is a 30A DC charge into the batteries.

Its really amazing to watch & I must admit this is my favourite way to connect a Kodak / Voltronics. It's really really robust & you can stack as many in a phase as you like. So you can have 3 machines in Phase A & 1 machine as Phase B & 1 machine in Phase C.

 

👌 I hope that sometime  in not too distant future , I  can present a Grafana hi-resolution log here in order to illustrate the interworking between consumers and producers on the Battery Bus  , using a topology where the PV string allocations of inverters are heavily unbalanced , in order to amplify and expose  the machines ability to democratically shave peaks of one machine in order to fill the valleys of another.

@James1

I have been down this road and had all the same questions.

Firstly, many installers will encourage you to drop the 3 phase and go for a 1 phase supply.  At some point in the future (if and when you get an EV) you may regret this.

I installed a Sunsynk 12kw 3P inverter as the most practical option.  Others have installed 3 x 5kw or 3 x 8kw single phase Sunsynk inverts to do pretty much the same job, obviously with a much higher output than my 12kw inverter.

If you are going for three inverters, common battery bank linked via a bus bar will work.

If you go the 3 inverter route, you then get the no. of MPPT's x 3 inverters.  On my 12 kw Sunsynk, I get 2 MPPTs.

What is important for the solar array is the voltage ... you have to have enough volts going through the system, but bot exceed the max volts.  You can start with an array or two linked to one of the inverters, usually the master.  If you go for a 5kw inverter, that will limit you to solar arrays of around 5kw.  If you want more panels, you would need to connect up to slave 1 and slave 2.

Please feel free to reach out to me and I'm happy to share my experience.

 

 

 

 

 

 

Thank you @JayN. I appreciate the help. I'm leaning towards the same option you have gone for - a 3P inverter.

In the same boat, thanks for asking the question so we could get some definitive information. Probably the biggest trap seems to be the grid tied inverters, which aren’t particularly useful for “our” purposes. 

So likely at least R50k is my estimate just for the inverter - Deye 12kw 3 Phase - Which is a stark contrast to 3 Axpert clones, although consideration to be applied to additional ancillaries required. 

 

 

Edited October 7, 20223 yr by Mosgi
Answered already