MPPT confusion

[shark1956]

After reviewing much of the online advice on MPPTs and solar panels, I am sadly confused. I have three 240W panels (and soon a fourth) that will need an appropriately sized MPPT charge controller for the two 12V 206Ah batteries. With Voc at 27.08v and Imp at 10.16A per panel, what is the optimal wiring and MPPT size I should buy? Would dual MPPTs be an advantage?
Thanks so much in advance!

 

[MisterSandals]

Assuming you are wiring your batteries as a 12.8V system (batteries in parallel):

240W x 4 = 960W
960W / 12.8V = 75A max charge

How fast to you need/want to charge your batteries? Can they handle 75A?

If you form your array with 2S2P configuration, you can use quite a few different SCCs because the Voc is pretty reasonable.
240W / 27.8V = 8.6A (Isc is 10.16A).
Your wiring and fuse/breaker from array to SCC would need to handle just over 20A.

If you run all 4 panels in series, a Victron 150/70 would probably be a very good fit. It would max out at 70A of charging but your array may never produce 100%. Your wiring from array to SCC would have to handle just over 10A (15A is good number).

Dual MPPTs? Do you mean 2 different charge controllers? Or something like the Morningstar SunSaver Duo which charges 2 different battery banks?
If you different SCCs, that would not add any efficiency or real advantages other than redundant systems.

 

[RandR]

You are where I was a few months ago, I am still working out the detail. Thanks in part to Mister. If you want better feed back on your system needs more information would be helpful. I want about 900W solar, I purchased a Victron 150/70. I am happy with it, but it is a little big for my system I think. I also 200AH of LifePo4 battery. I am a work in progress, thanks Mister!

 

[MisterSandals]

I want about 900W solar, I purchased a Victron 150/70. I am happy with it, but it is a little big for my system I think. I also 200AH of LifePo4 battery.

I am likely going to buy a 150/70 within the next hour. I have 2 new 400W panels to charge a big (to me anyway) bank of 16x 280Ah EVEs i am top balancing right now. I am still working out details on this now too! My heart and my head are at odds whether to go with 24V or 12V battery/BMS/inverter ...

 

[RandR]

Hate to derail this thread but… I am a rank amateur at this but I wish I had done a 24V system, from everything I know, which is very little! Nice thing is as far as the MPPT it is voltage sensing for 12/24/48V systems. Good luck!

 

[rmaddy]

How fast to you need/want to charge your batteries? Can they handle 75A?

The OP stated 12V 206Ah. That sounds like SOK batteries. SOK have a recommended charge current of 40A. So two in parallel can handle 80A.