Crystalline silicon is the dominant semiconducting material used in photovoltaic technology for the production of solar cells. These cells are assembled into solar panels as part of a photovoltaic system to generate solar power from sunlight.
Crystalline silicon (c-Si) cells are obtained from thin slices of silicon (wafers) 160–240 μm thick, cut from a single crystal or a block. The type of crystalline cell produced depends on the silicon wafer manufacturing process
Crystalline silicon cells are made of silicon atoms connected to one another to form a crystal lattice. This lattice provides an organized structure that makes conversion of light into electricity more efficient.
More info on crystalline silicon here
Did you know?…….
The first solar  silicon solar cell was invented in 1941 by Russell Ohl (read here)