The regulator should not allow the voltage to get that high in charging your 12V batteries. 15V for equalization, 14.2V for bulk, 13.8 for absorption and 12.8-13.2 for float. if your reg say each 12V, 200W panel is charging 10-11 amps, this is the most accurate way to work out max current for the 4x200W panel array. Still allow for greater current unless as you say the reg will prevent the extra current the reg's not designed to produce. Sunny day with cooler wind on panels may produce more current/power.Thanks for the info Scott.
As far as I can see, all panel specs I look at state the watts divided by the maximum voltage, for example 200watt panel divided by 18volts = 11amps, and that's about what the regulator says at full sun , about 10 - 11 amps. Maybe I could get more out of it if I position the panel better. This is the specs for my panels, and I did a search on different panels and it seems they all do the same.
I didn't know that about cable size, but I checked today and all my cable is 10mm
I didn't get them hooked up today, i'm still working on how to mount them with brackets etc
It's been a while since I needed to know exact charging voltages, so a google would be advised