The basic principle involved in working of a PV cell is the Photoelectric effect. . In this effect electron gets ejected from the conduction band as a result of the absorption of sunlight of a certain wavelength by the matter. In photovoltaic effect, when a photon particle hits a PV cell, some portion of the solar energy is absorbed in the semiconductor material as shown in below figure 2.1.
Figure 2.1 Working of solar cell
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.