Semiconductor grade (also solar grade) polycrystalline silicon is converted to single crystal silicon - meaning that the randomly associated grains of silicon in polycrystalline silicon are converted to large single crystals of silicon. Single crystal silicon is used to manufacture 99% of all electronic devices. The devices are used in watches, refrigerators, microwaves, televisions, radios, communications equipment such as cell phones, and controls for cars, ships, aircraft, missiles, and atomic weapons.