For a 12 volt battery bank, is it better to wire panels in series or parallel?

[stuman]

I have three panels with open circuit voltage of 30.  I currently have them setup in series for 90 volt nominal.  This is within the limitations of the 150 Classic I have, but with a 12 volt battery bank, I want to know if I'm making it work too hard.  Would I be better off wiring in series for 30 volts input? 

This is one string of the panels from my home system, which is a 48 volt bank, so 90 volts makes perfect sense there.

My controller tends to run pretty hot sometimes...to the point that I've had to remove the cover to allow the circuit to be cooled by a passing air conditioner stream.  Panel wattage is 240 each for a total of 720.  I've pulled 3.7 kwh in a single sunny day with flat mounted panels...on an RV roof.

I turn the air conditioner on and off as a slow diversion load from aux1 in order to have it not run if insufficient battery voltage is present.

[CDN-VT]

Im thinking 3 panels at 7 amps = 21 amps for a run of how long ? Wire size enough to handle to & from the panels to the cc? then see if the temps under the menus is much lower with the same / similar harvest .
What were your temps you experienced . Mine are 52 & 55 c

VT