This site will tell you what you need to know. I put 100 watt panel on my Roo, with a Morningstar controller. I have two batteries, and led lights, and it will run everything I need, including running the furnace for a couple of hours in the morning until the sun comes up. I don't run my furnace at night because it wakes me up. I purchased my flexible panel from a guy on eBay who sells out of Albuquerque. Convenient, since I live here. I attached my panel with silicone. I tried to remove my last solar panel when I sold my camper, and gave up. Critical to have large wire from panel to battery, I like circuit breakers better than fuses (you can get them at auto supply store).