No, solar PV panels come in a variety of forms.
There are two main types of solar cells that differ in the arrangement and number of silicon crystals. Polycrystalline panels are made from wafers created by cutting thin strips from a solid block of silicon. These are relatively cheap to manufacture and historically have had lower efficiencies than other panel types however technology has improved to increase it so the difference is much less significant. Polycrystalline panels usually have a blueish tint.
Monocrystalline cells are usually black and have a single silicon crystal. They are efficient and perform better in low light conditions than polycrystalline panels.
There are a myriad different options in terms of frame and backing sheet colour, efficiencies and panel dimensions. Panel outputs have increased over time as the technology has improved.