You are on the border line in needing a regulator. You didn't mention how big your battery bank is. You'd best disconnect the shore power charger
as this panel should keep the batteries charged and recharged with the intermittant drain you'll probably have on the battery. Leaving the shore charger
hooked up will surely overcharge the batteries in conjunction with the panel. Might think about adding a second battery if your current
one is a standard Group 27 12volt battery. YOu'll get more benefit from the extra battery than from a charge controller.
the battery fluid levels. If that is going down appreciably over a 3 month period, then add a charge regulator as you are sending too much juice to the batteries and risk damaging them.