After receiving energy from sun, the electrons from valence band jumps to the conduction band, when absorbed energy is greater than the band gap energy of the semiconductor. Due to which electron-hole pairs are created. Now the electrons in conduction band become free to move. Movement of electrons create positive and negative terminal. These free electrons are enforced to move in a particular direction by the action of electric field present in the PV cells and also create potential difference across these two terminals. These electrons flowing comprise current and can be drawn for external load. This current and the voltage produces required power when connected to external circuit.