There are a couple of kinds of flexible solar panels. The amorphous silicon ones are really flexible, you can roll them up. These are about half as efficient, e.g., twice the area needed for the same power. The other kind are semi-flexible, usually laminated onto a sheet metal backing. The best of these use the same mono crystalline cells as rigid panels. You can only bend them a little, usually 3% arc is specified. They can be glued directly to a surface. They are 2 - 3x the price of rigid framed panels, and since they cannot get cooling air underneath will run hotter (which reduces output some). But you cannot beat the clean low profile installation, and they are usually walkable. Got a bunch on my boat:
