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I am wiring a smartsolar mppt 100/50 into my system.
Can you tell me if the negative pv current needs to run through the controller or does it just need a voltage reference -ve.
pv -ve and batt -ve appear to be common inside the controller but is there a shunt between them?
I want to use a negative bus bar to connect all pv -ve's and also feed the battery -ve and one controller -ve from the same star point. is this ok?
The negative terminals of the MPPT are common, the MPPT's (at least the 100/50) measure the charger current in the positive output from the buck converter, so I would expect Victron to retain this throughout the range.
The MPPT DOES sense the battery voltage and the PV voltage at the input terminals however, so the volt drop in your negative cable due to charging current will also affect the PV voltage. However this will be minor if the cable is well sized. The PV current will deduct from the Charging current in the negative, reducing the current in this cable. Beware of creating cable loops though.
Thanks for the replies, I'll consider how the volt drop will effect things.
My connection from mppt to the star point will only be 40cm and star point to battery less than 150cm so the volt drops will be tiny especially if I use 16mm2 cable.
cheers.
Bob
