I am visiting Florida for the first time and while driving around I noticed many of the houses have wide black strips on their roofs. They look like fabric but they might be solid. They don’t cover the whole roof, and they’re not long enough to reach the rain gutters, so what purpose do they serve?
Solar water heaters, perhaps? Your description doesn’t ring any bells…
Solar water heaters are the only thing that makes sense and the really thin ones (that could look like fabric from a distance) are usually used for heating swimming pools.
There are a large number of swimming pools in this area (it’s very affluent), so solar water heaters makes the most sense. I suppose they would be handy in the winter…