The fundamental principle of photovoltaic power generation is the photoelectric effect of semiconductors. When a photon shines on a metal, its energy can be absorbed by an electron in the metal. The energy absorbed by the electron is large enough to overcome the metal's internal gravity to do the work of escaping from the metal's surface and becoming a photoelectron.
Silicon atoms have 4 outer electrons. If pure silicon is combined with 5 external electrons, such as phosphorous atoms, it becomes an Ntype semiconductor; If pure silicon is combined with 3 external electrons, like boron atoms they form a P-type semiconductor.
When Ptype and Ntype are combined, the contact surface will form a potential difference and become a solar cell. When sunlight hits the PN junction, the holes move from the area of the P pole to the area of the N pole, and the electrons move from the area of the N pole to the area