If you have two matching 120W panels, those are each close to 7 amps each charge rate. Why even bother screwing with the 50 watt solar panel and it's measly 2.5 addtional amps, when you already have 14 amps? Get another matching 120W panel if you can, and sell the 50 watt panel.
120W panels for 89 AH group 27's AGM's is plenty, for most applications.
Next time when your replace the Group 27's Trojans, consider 6V T105's instead. Much, much, much easier to keep charged, they don't have the crappy acid to lead ratios that car type sized batteries do, so that the damn battery can fit under the hood without shorting out at the terminals.
Trojan should make a T-105 AGM Side terminal batteries for cars already, for no shorts.
When you match batteries, you should match panels also... seems to me just to be common sense.
