Series-Parallel Wiring to 12V battery

[pdaddy]

I have 4 200w solar panels that I want to wire in series-parallel on top of my travel trailer (currently only have 1 200w panel). I plan to use a 20a fuse for each string. I have a 12v 200ah LifePo4 battery, 60a MMPT solar charge controller and 1000w inverter.
Question #1: how do I calculate the total output (in volts/amps/watts) this configuration will send to my solar controller?
Question #2: if the voltage is more than 12v, does the solar controller regulate that to ensure only 12v is going to the battery (probably not good sending 24v to a 12v battery).
Question #3: I want to ensure I'm using large enough wire throughout the system. Will 6 awg be enough? (that is the max my solar controller will accept). I also have 2 awg from the inverter to the battery.

 

[sunshine_eggo]

I have 4 200w solar panels that I want to wire in series-parallel on top of my travel trailer (currently only have 1 200w panel). I plan to use a 20a fuse for each string.

So, 2S2P config.

Single string or 2P arrays do not require fusing (3P and higher do); however, there is no harm doing so. Do not exceed the max fuse size typically published on the back of the panel.

I have a 12v 200ah LifePo4 battery, 60a MMPT solar charge controller and 1000w inverter.

60A * 14.4V = 870W - covers the 800W nicely.

Question #1: how do I calculate the total output (in volts/amps/watts) this configuration will send to my solar controller?

Panel Voc * 2 = maximum voltage the array can subject the MPPT to - must be well under the max allowed to allow for cold temp voltage increases (in denver, I'd allow at least 20%, i.e., multiply your Panel Voc *2 by 1.2, and it should still be under the max voltage of the MPPT).
Panel Isc * 2 = maximum current the array can send to the MPPT.
Panel Vmp * 2 = total array voltage at max power output.
Panel Imp * 2 = total array current at max power output.

(Panel Vmp *2) * (Panel Imp *2) = Max array output = 800W

Question #2: if the voltage is more than 12v, does the solar controller regulate that to ensure only 12v is going to the battery (probably not good sending 24v to a 12v battery).

The controller should be programmed for the correct system voltage. You will also program your desired bulk/boost/absorption (different label for same voltage) and float voltages as well as other parameters.

Question #3: I want to ensure I'm using large enough wire throughout the system. Will 6 awg be enough? (that is the max my solar controller will accept). I also have 2 awg from the inverter to the battery.

10awg (30A) should be fine between the PV and MPPT. 6awg THHN typically used in household wiring is typically only rated for 50A. If you use fine strand "welding wire" or wiring listed as "battery wire," 6awg will be fine. Example:

6 Gauge (6 AWG) Battery Cable with Ends OFC Copper Flexible Stranded UL MTW/THW/SGT

www.batterycablesusa.com

You WILL need a fuse between MPPT and battery. Fuses are sized 1.25X wire rating/max possible current rating (if wires are oversized). In your case a 75A (maybe round up to 80A if 75A unavailable) fuse is required.

 

[pdaddy]

So, 2S2P config.

Single string or 2P arrays do not require fusing (3P and higher do); however, there is no harm doing so. Do not exceed the max fuse size typically published on the back of the panel.



60A * 14.4V = 870W - covers the 800W nicely.




Panel Voc * 2 = maximum voltage the array can subject the MPPT to - must be well under the max allowed to allow for cold temp voltage increases (in denver, I'd allow at least 20%, i.e., multiply your Panel Voc *2 by 1.2, and it should still be under the max voltage of the MPPT).
Panel Isc * 2 = maximum current the array can send to the MPPT.
Panel Vmp * 2 = total array voltage at max power output.
Panel Imp * 2 = total array current at max power output.

(Panel Vmp *2) * (Panel Imp *2) = Max array output = 800W




The controller should be programmed for the correct system voltage. You will also program your desired bulk/boost/absorption (different label for same voltage) and float voltages as well as other parameters.



10awg (30A) should be fine between the PV and MPPT. 6awg THHN typically used in household wiring is typically only rated for 50A. If you use fine strand "welding wire" or wiring listed as "battery wire," 6awg will be fine. Example:

6 Gauge (6 AWG) Battery Cable with Ends OFC Copper Flexible Stranded UL MTW/THW/SGT

www.batterycablesusa.com

You WILL need a fuse between MPPT and battery. Fuses are sized 1.25X wire rating/max possible current rating (if wires are oversized). In your case a 75A (maybe round up to 80A if 75A unavailable) fuse is required.

Thank you for the detailed response. Much appreciated.