DIY Powerwall / Battery

[okeydokey]

I really have not a clue if the following is daft or even possible - please tell me gently
Would you be able to have 3 in parallel with a switch on the third so you can isolate it easily - then have 2 connected on good sunshine days and bring the 3rd in when the sunlight is not so productive?
Also could the switch be voltage activated so when the input on 2 is low it brings in the 3rd and when too high drops the 3rd?

 

[johnb80]

I would put the pair in series and buy another MPPT charger for the odd 3rd panel to charge batteries, they will then all feed your system.

 

[John Brown]

I really have not a clue if the following is daft or even possible - please tell me gently
Would you be able to have 3 in parallel with a switch on the third so you can isolate it easily - then have 2 connected on good sunshine days and bring the 3rd in when the sunlight is not so productive?
Also could the switch be voltage activated so when the input on 2 is low it brings in the 3rd and when too high drops the 3rd?

As the other Johnb pointed out, two in series means a higher voltage, which means the battery starts charging at lower light levels. Three in parallel could exceed the max current of the charge controller, but that doesn't matter, as the charge controller decides how much current to take. So a switch to isolate wouldn't really be necessary in a 3P situation. In a 3S situation, one could, I suppose, switch a panel out of the circuit on sunny days, but it would be tricky to predict and not exactly failsafe.

 

[John Brown]

I would put the pair in series and buy another MPPT charger for the odd 3rd panel to charge batteries, they will then all feed your system.

What? Another MPPT in parallel with the existing one? Would that work OK?
To be honest, I think an approximate doubling of input power will serve my needs, although I'd buy another 24V LiFePo4 and parallel it if they weren't so dear.