The Principle and Manufacturing Process of Photovoltaic Power Generation

The main principle of photovoltaic power generation lies in the photoelectric effect of semiconductors. When photons irradiate a metal surface, their energy can be fully absorbed by a specific electron in the metal. If the energy absorbed by the electron is sufficient to overcome the internal gravitational work of the metal, the electron will escape from the metal surface and become a photoelectron.

A silicon atom has 4 valence electrons. If pure silicon is doped with atoms that have 5 valence electrons (such as phosphorus atoms), it becomes an N-type semiconductor; if pure silicon is doped with atoms that have 3 valence electrons (such as boron atoms), a P-type semiconductor is formed. When the P-type and N-type semiconductors are combined, a potential difference is created at the contact interface, which serves as the basis of a solar cell. When sunlight irradiates the P-N junction, holes move from the P-region to the N-region, while electrons move from the N-region to the P-region, thereby generating an electric current.

The photoelectric effect refers to the phenomenon where light irradiation causes a potential difference between different parts of a non-uniform semiconductor or between a semiconductor and a metal. It involves two main processes: first, the conversion of photons (light waves) into electrons, i.e., the transformation of light energy into electrical energy; second, the formation of a voltage.

Polycrystalline silicon undergoes processes such as ingot casting, ingot breaking, and slicing to produce silicon wafers to be processed. These silicon wafers are then doped and diffused with trace amounts of boron, phosphorus, and other elements to form P-N junctions. Next, screen printing is used to apply a precisely prepared silver paste onto the silicon wafers to create grid lines. After sintering, back electrodes are fabricated simultaneously, and an anti-reflection coating is applied to the surface with the grid lines—thus completing the production of solar cells.

Solar cells are arranged and combined into solar cell modules, which form large circuit boards. Typically, the periphery of each module is enclosed in an aluminum frame, the front side is covered with glass, and electrodes are installed on the back side. A complete photovoltaic power generation system can be assembled by integrating these cell modules with other auxiliary equipment. To convert direct current (DC) into alternating current (AC), a power inverter must be installed. The electricity generated can either be stored in batteries or fed into the public power grid.

In terms of the cost structure of a photovoltaic power generation system, solar cell modules account for approximately 50%, while the remaining 50% comes from power inverters, installation fees, other auxiliary components, and miscellaneous expenses.