Put "simply," a photo-voltaic cell is comprised by a series of photodiodes.  Photons from light propel electrons associated with the metallic substrate of the solar panel into a higher energy state that are then displaced, creating direct current.  A large number of cells are contained in an individual panel, the total output of which varies as a function of the rating of the photodiodes used and the number that are accommodated by a single panel.  Photo-voltaic technology is one of the very few sources of power that does not derive from the turning of a coil of copper wire around a magnet, and it is a completely carbon-neutral source of power.