Under the fierce SoCal and Baja sun my awning started falling apart after 2 years - while still rolled. The vinyl on the top exposed part was crumbling to dust.
Following nice pictures by somebody posted here, I put a cover made of 2 pieces of aluminum gutter, overlapping and sliding into each other in the middle. Plastic gutter shape didn't worked well for me. In heavy wind those 2 pieces have lifted up in the middle, separated from each other and fell down, hanging at the ends where they were attached to the awning mounts. Winds here throw lawn chairs and small items around like they are made of toilet paper, I rarely even unroll this awning, but it sucks watching it crumbling. So I riveted 2 pieces together in the middle.