Series wiring will be just like the 6V battery wiring... Series will add the voltages coming from each panel however the current which is also very important will only be as high as the lowest panel DC current output...
for instance with my two batteries in my battery bank I would want the solar controller to provide 14.4VDC @ 40 Amps DC capacity if I wanted them to recharge in a three hour periods. Battery science tells me each battery needs 14.4VDC with 17-20AMPS DC current for each battery in the bank to recharge from a 50% charge state to a 90% charge in a three hour period... That would be alot of of solar panels since a typical 120WATT panel only produces around 5-6AMPS DC current.
So in this case I can probably come up with enough panels (two each 120WATT panels and one 240Watt Panel) to give me 17-20AMPS DC current wired in parallel and then would have to plan on a longer time frame of being in the high sun to get them charged up since it is feeding multiple batteries.
This is the way I understand at any rate...
Roy ken
