A semiconductor is a material exhibiting properties of both electrical conduction and insulation.
A Conductor allows electrons to become 'excited' and flow - such as electrical current flowing through copper wire - a conductor.
Insulator materials resist or block the flow of electrons - such as plastic coatings on electrical wires - which enables control of where the current moves.
Semiconductors are the driving force of how solar panels work - many solar cells (made of semiconductor materials) are used in solar panels.
For solar panels, the commonly used semiconductor is silicon, mainly crystalline silicon. However other semi conductor materials are increasingly being used, such as amorphous silicon, and compounds such as amorphous silicon, arsenic, selenium, tellurium, germanium, and gallium arsenide.