I am planning a new 100% off-grid 3-phase system for a home in Spain and planning out the loads across the phases, it will be impossible to get them balanced. If I use 1 x 5kW multiplus II per phase can it run completely unbalanced? e.g. L1=5kW, L2=200W, L3=0W
Secondly, if I already have a single phase generator, can I connect it up only to the most essential phase (L1) and have it pass through and charge the battery?
Finally, if I AC couple a 3-phase Fronius inverter on unbalanced phases will it automatically figure out where to send the power?
The biggest 3 phase load will be an air source heat pump, borehole pump and in the future EV charger. But right now, it will mostly be regular 1 phase household loads sprinkled across the phases as best I can. Reason for 3 phase is that it can handle larger EV chargers, and the distance to the pump is about 300m.
Please be aware, you cannot use all kinds of 3-phase loads. I think only star schema is allowed and not triangle. Please check the manual.
I use a 3-phase 2kw vacuum pump on 1-phase by using a 1-phase variable frequency device (VFD) to generate 3 phases. Might be a solution for the pump. Classic solution for long distance is increasing voltage by a transformator and lowering on the load side. This will also isolate the pump from the house.
Please mind, the MP2 5k can supply 4000W not 5000W at a temperature of 25C. In Spain you might need to cool it.
Yes, you can add unbalanced power sources, where a 1-phase generator is an extreme example. I use several 1-phase micro grid inverters (on ACout). They produce power on the single phase independently.
Please mind the factor 1-rule for Fronius and generator. Ensure the genertor does not start when Fronius is pushing a lot of energy and battery is full.
@Björn - regarding 3-phase loads. I’m still struggling to receive final confirmation on this topic - i have 3-phase air compressor. It is standars 3-phase 400 VAC induction motor so L1/L2 and L3 is only connected. Is it ok to use 3x Multiplus II 48/5000 to drive it among other things in house? In fact i just sold those 3 MP II and need to decide whether to go with three 6k5 models (big aluminum story…) or three MP II 48/8000 units. Need to power my entire house and i like to do something in ma garagge thus 5.5kW compressor and 3-phase plasma (i think up to 7kVA) cutter powering requirement as an addition to the rest of the house. Also i’m installing air condition (around 3kW consumption) but those units are only 1-phase devices. So the will be big unbalance.