2 MPPTs; 2 Batteries; 1 Solar Array???

[jpcjtrtj]

I have two 100 Watt panels on the roof of my RV. I have an external port so I can add two more panels on the ground to double the input to 400 watts if necessary. The roof panel has a solar disconnect; the ground panels do not. Their cutoff is connecting or disconnecting them from the port. To be super careful, i can flip them over so they are not charged when I disconnect or disconnect in the evening.

The two sets of wires from the arrays (ground and roof) join up after the roof solar disconnect. Thus, it is possible to run either just the roof in 2S (disconnect off and no ground panels); or just the ground in 2S (disconnect off and ground panels connected) or both (disconnect on and ground connected) as a 2S2P into the existing MPPT controller.

The MPPT controller can be turned off and its output has a breaker that also can be turned off on the battery side, but not on the PV side. So, my question is can i turn off the house battery MPPT, trip the breaker, and use the power coming from the roof solar to charge a small 60 amp hour battery that has it's own mppt charge controller through the ground connection or will that cause problems? I suppose i could hook the ground panel wires into the circuit above the cutoff switch to cut out the house MPPT entirely when the disconnect is activated, but that would be a pain just now and would eliminate using only ground panels when the roof is shaded. I tried to draw a basic sketch of the circuit below. the 40 Amp fuse is a breaker; both MPPTs are Victrons.

 

[0truck0]

is hard to follow... No.
I would put the breaker on the panel side. I have breaker on BOTH sides. Directions always say disconnect the panel before disconnecting the battery, so the answer is, no.

WIth breaker/switch between the panel and the mppt then you have better setup. No harm comes from not having a switch between battery and mppt. I guess is fine to flip ground panels over so they have zero voltage.

Yes, you can switch off panel then move the charge cables from the mppt to another battery and then switch it back on. The batteries both need to have the same charge profile because you likely have mppt programmed for a single method of charging and single voltage (12 or 24).

You can simply use a selector switch to move the positive from mppt to either battery and the switch happens so fast that prob ok to not disconnect the solar panel (dont quote me on this), safer to disconnect solar panel, switch batteries, then connect panel back. Incidents rarely happen if you do not disconnect panel first, but incidents can happen, so safer to follow the process.

 

[pollenface]

You can use 1x mppt and 1x pwm if you're stuck for options, won't hurt anything.