Two Parallel MPPTs, One trips the breaker

Q&A and troubleshooting
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1

My wife and her friend just bought a used fully electric boat (river ferry). So I have become the engineer. I’ve mostly got a handle on everything, added bluetooth dongles where I could, and added home assistant system to monitor everything.

The original system included

  1. SmartBMV BMV-712
  2. BatteryProtect 48V/100A x2 (one on each 6kW epropulsion electric motor)
  3. SmartLithium 24V/200Ah x4 (wired parallel set of 2 in series)
  4. BlueSolar MPPT 150/35 x2
  5. Multiplus 48V/3000-16 230V
  6. flexible solar panels 4x unknown

I have since added

  1. Bluetooth dongle for each MPPT
  2. VE.Direct Bluetooth dongle for the Multiplus
  3. Orion Tr 48/12 20A Charger - to charge the 12V house battery (currently a 100Ah AGM)
  4. Orion 48/12 20V converter - backup house supply.

Initially the inverter’s AC output was not connected, but the shore AC input went to the multiplus to charge, and to a few point points. I rewired there power points to inverter’s output. so we have full time 230V. This fully time 230V supplies 5G modem/wifi, mini computer running home assistant under proxmox.

The 4 solar panels are wired two in series, each pair to a MPPT (port and starboard). The panels go though a double pole breaker (noark k 10A) for both +ve and -ve leads, to the MPPT, then its outputs through another double pole breaker (noark k 16). The output of these 16A breaker are wire in parallel with the other solar cell output path, and then to the batteries.

Now the problem. When the MPPT are activity changing, one pole of 16A breaker (-ve) on one side of the system (port) often pops. I have turned charging rate down to 8A, and it still occasionally happens. Actually, have since both side port/starboard trip this breaker. I haven’t been activity monitoring when this happens.

Any idea why? faulty breaker, wrong type of breaker, mismatch between the two sides? Why shouldn’t I replace these with a 35A break to match the MPPT (even through the panels will not provide this).

Mark

2

A little more info, I capture the breaker tripping:

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image1668×1231 404 KB

It looks like I limited the starboard MPPT to 10A, the port to 8A. The Starboard tripped. I temperature of the multiplus right next to the MPPTS was 28C.

3

What do you mean with

“Now the problem. When the MPPT are activity changing, one pole of 16A breaker (-ve) on one side of the system (port) often pops“

Do you mean the 230V shore power breaker (ACin of the MultiPlus)?

If yes, it sounds like it try to feed in to the shore power socket.