Solar panel for m' home, fitting advice please

[R TOY]

Having just replaced yet another leisure battery (discharged during winter) I figure I need a solar panel to keep things charged.
I see most panels advise having a controller in the circuit. Is this really necessary for say an 80w panel connected to a 110 ah battery ? The highest charge would only be around 3-4 amps (if my workings correct)
The main reason I would like to avoid a control box is that I have a 12v supply up on the roof which runs a bedroom fan/vent. My plan is to connect straight to this circuit which then feeds back to the battery without any more routing wires through the van.
Simple in my mind but will it work ok ?

Anyone have experience of fitting solar panels with info to share ?

Thanks Dave

[R TOY]

Thanks folks, looks like my quick fit plan may be flawed..