Solar wiring issue

I'm sure solar questions have been beat to a pulp but I just can't find the answer.

I don't want to drill holes through my rv roof and found that I could easily run my solar power lines down my fridge exuaghst vent. Thus gives me great access to everything I need.

Question is, can I just use the power lines coming from my battery to the fuse and breaker box to back feed my solar to charge the batteries? Or do I need to run new lines all the way back to the batteries from my control?