The type that produces electricity is known as photovoltaic (PV) and comes in three basic forms,

Monocrystalline. These cells are cut from a single crystal of silicon, or a singe slice from a crystal.  It has a smooth texture and the thickness of the slice is visible. These are the most efficient and most expensive to produce. They are rigid and must be mounted in a rigid frame to protect them from fracture.

Polycrystalline (or Multicrystalline) These cells are a slice cut from a block of silicon, made up from a large number of crystals. They have a speckled reflective appearance and the thickness of the slice is visible. Polycrystalline cells are slightly less efficient and less expensive than monocrystalline cells and also need to be mounted in a rigid frame.

Amorphous cells are produced by bonding a thin film of amorphous (non crystalline) silicon onto a variety of substrates. They are the least efficient and least expensive to produce. The amorphous (non crystalline) silicon in a thin layer is flexible, and if bonded to a flexible surface, the whole solar pv panel can be flexible.  The power output of amorphous solar cells reduces over time, especially during the first few months, until they become basically stable. The quoted output of an amorphous panel should be that produced after it has stabilised. These are more commonly found on the curved cabin roofs of boats etc