1) Should the length of the cables from the MPPT to the "bus bar" be the same?
2) Should the length of the cables from the inverters to the "bus bar" be the same?
3) Could the length between MPPT and the inverter be different?
Thanks to anyone who can give me advice on the design
1) No.
2) If multiple inverters connected, total length of (+) and (-) should be the same.
3) If you have a bus bar, the MPPT should not be connected to the inverter.
The length from the mppt to the bus bar can be what it needs to be, it is not related to what the inverters needs.
All inverters in one system should have equal length cables. So if you have three, your longest run is the length for all. (And dont forget to size up if it is long)
What does change when you have longer runs is the cable size even on the mppt (unless you have gone as big as the terminal can take) A longer run needs bigger cable. The product manuals give good guidelines.
Ok thanks to all,
even if it would seem that from the victron manual "Wiring-Unlimited-EN.pdf" it is necessary to keep the same length also for the MPPTs. See page 38.
My only doubt remained between the length of the cables from mppt to the "bus-bar" and that between MultiplusII and the "bus-bar", if these should also be the same.
The mppt and the inverter do not have to have the same lengths as each other
When using multiple inverters it's important to have each having the same cable size/length/resistance to the battery/DC bus.
For MPPT charge controllers, it's not important, but having equal length cables to each charge controller will mean that their sensed voltage of the battery/DC bus will be similar. If the MPPT charge controllers are getting their voltage sense readings from somewhere else like DVCC, a SmartShunt or shared using a smart network, then the advantage of the same length cables is not there.
