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teubeli avatar image
teubeli asked

3Phase MultiplusII 48/8000 or 48/10000 on 9 Pytes V5Alpha batteries.

I plan an ESS system with possibility for Island Mode. I have AC coupled 22kW PV with 2 Fronius inverters 10 and 12kW. Usually the Peak perfromance is approx 17-18kW. Now I want to add a 3-Phase ESS system and the Factor 1 Rule dicteates at least 3 Multi 48/8000 eq. 24kW. However, the the battery system with 3 towers at 3 Pytes V5A provides me a charge and disccharge Current of 300 A per tower eq. Total 900A. The Multis only deliver 110 A max each for Charge and disccharge current.

So far all good. The question is, in case in Winterseason I have emptied the batteries during night and morning hours and arround midday I would have 1-2 h of Sun, the Limitation of charging the batteries would be in this case the Multis. corrct?

So woul dit be worth installing the 48/10000 instead and raise the max current to 140A each (total 450A so that what ever my PV is capable of, the Multils can back into the batteries?


Any input is appreciated and if this is a increadibly stupid question please let me know and explain what I might have missed... :-)

 
               
 
              
 
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               Alexandra avatar image 
             
 
             
 
              
 
               Alexandra 
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@teubeli 

                 
I can't answer from a cost perspective but switching some PV to DC based mppts is the best option. Then there is less conversion as it goes straight to the battery bank and you are not limited in any other way unless you have a poor DC wiring set up.

                 
AC charging hard will cause inverter and inverter/charger derating because of heat. (Unless you have air conditioned the room or have amazing ambient temperature.) So even if you uprate the inverter you still are not likely to see the full 140A per phase.

                 
On a side note if inverter derating for load reasons is a consideration them maybe get the bigger inverters. But still get DC based mppts anyway it is always a good combo for moving off grid anyway....

                
 
               
 
              
 
               
               
              
 
               
 
               
 
                 
                 
                 
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                   teubeli avatar image 
                  teubeli  
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                    Hi Alexandra. Thanks for the answer. The PV is a high voltage system and already in place for some years, so chaning that setup is not part of the plan. Also when it comes to optimize the own consumption (use when and what's there) I think the high Voltage PV systems directly into AC is the most efficient way. My plan is not moving off grid but in an outage being able to sustain for some hours/days in max. 
                  
 
                 
 
                 
 
                   
                     
                     
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                    Alexandra avatar image 
                   Alexandra ♦ 
                      teubeli   
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Not so for battery charging since you are concerting dc to ac back to dc.

                    
But direct to loads i can agree it is more efficient to have ac pv.

                    
You can do what you like there but expect derating due to heat so it wont work out how you have planned it.

                   
 
                  
 
                  
 
                    
                      
                      
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Related Resources
 
           
 
           
 
            

            
MultiPlus-II Product page 

            
MultiPlus-II Manual

            
Multiplus-II GX Online Manual

            
MultiPlus-II 230V Datasheet 

            
VE.Bus Error codes

            
 
            
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