You only get full AH yeild all day when the batteries remain thirsty enough all day to accept the most amps the array will provide. (Ignoring the drop in amps as battery voltage rises due to the panel's IV curve.)
This brings the array size/battery capacity ratio into play. Also if you have trees to the east and none to the west, you don't get the theoretical mirror image.
If it is unobstructed east to south, then you can grab that and double it, regardless of what happens in the afternoon. This goes to heck when your morning cloud cover takes awhile to "burn off" but the sky is clear in the afternoon. Nobody said this solar stuff behaves itself!
