One thing no one has brought up. WIND! My roof panel is solid as a rock as is the camper in a bad storm on the beach in NC.
It doesn't take much of a gust to put the portable as risk of falling "glass panels". I haven't fullly worked out my leg system yet. but to prevent being blown around in modest winds it would have to be staked or weighted.
This is not a point to be ignored, as I recently learned the hard way. First night camped on the White Rim Trail earlier this month, a strong wind came up during the night. I had deployed my portable panel to catch the morning sun, instead it caught a sharp rock on its face when the wind flipped it during the night. The tempered glass was totally shattered. Interestingly enough, the panel continued to work through the trip, but only at about 1/3 of its usual output.
I'm replacing the 100w portable/deployable panel (but will be more careful and lay it flat overnight.) I am also going to add a second 100w panel to the roof. This will give me the best of both worlds: I can aim the deployable panel at the sun when I need a boost, but the roof unit will work all mid-day. There is definitely some overhead in time and effort to deploy the portable panel, so if my batteries are well charged I'll skip that step. Yet, if I set up with the camper in the shade, my cable is long enough I can set the portable out in the sun.
In fact both panels arrived today from Amazon. They have a slightly lower profile than the old one, though length and width are the same. They also weight 18# each, where competitor's panels are 20#. These are polysilicon from Windy Nation.
I found this thread while trying to figure out how much air gap to put between the solar panel frame and roof when I fabricate my custom mounts. Any suggestions? I'm thinking about half an inch to keep the overall profile low, but still allow the heat to escape.