I have a large 85 watt solar panel I was told that i should use a 15 or 20 amp controller.
The cheapest i found was £15.00 GB Pounds from eBay...
Fitted into a lift up hatch It does keep both 120 amp batteries fully charged...With no Problems.
See Here PAGE 12
By the way there is Nothing stupid about asking questions.
After all how would we know the answers..