Composition of a Photovoltaic Power Generation System
Photovoltaic power generation is a form of electricity generation that utilizes the photovoltaic effect in semiconductor materials to directly convert solar energy into electrical energy. When light shines on a solar cell and is absorbed in the junction region, photons with sufficient energy can excite electrons from covalent bonds in both P-type and N-type silicon, thereby generating electron–hole pairs. Before electrons and holes recombine near the junction, they are separated by the electric field of the space charge; the electrons then move toward the positively charged N-region, while the holes move toward the negatively charged P-region, ultimately establishing a voltage between the P- and N-regions. The generated electrical energy is subsequently converted—via power electronic devices such as step-up/step-down converters, inverters, and rectifiers—and finally transformed into usable electrical power.
A solar photovoltaic power generation system primarily consists of solar cell modules, rectifiers and inverters, battery charge–discharge controllers, other energy storage and auxiliary power-generation equipment, electricity purchase and sale metering instruments, as well as computer-based monitoring and other power electronic devices.
1, the core of the solar photovoltaic power generation system—the photovoltaic module array
A photovoltaic module array consists of several photovoltaic modules or panels assembled together mechanically and electrically in a specific configuration, mounted within a metal frame, and protected by a glass cover. Under sunlight, it converts solar energy into electrical energy for output.
2, battery
The energy storage component of a solar photovoltaic system is the battery. During normal power generation, the battery stores the electrical energy produced by the solar panels; when sunlight is insufficient, at night, or when the load demand exceeds the output of the solar panels, it discharges a portion of its stored energy. Currently, the most commonly used batteries are lead-acid and lithium-ion types. Lead-acid batteries include valve-regulated sealed lead-acid batteries designed for deep discharge and absorbed‑glass‑mat (AGM) lead-acid batteries with deep-discharge capabilities. Lithium-ion batteries represent an important direction for future development.
3, controller
The controller improves the efficiency of the battery, while also specifying and controlling the charging and discharging conditions, and regulating the output from the solar panel array and the battery to the load according to the load’s power requirements. The rapid growth of the solar photovoltaic industry has placed numerous demands on the power grid; as a result, controller functionality is becoming increasingly sophisticated, with a growing trend toward integrating traditional control functions, inverters, and detection and monitoring systems.
4, inverter
An inverter is a device that converts the direct current generated by solar panels into the required alternating current. The converted AC can be coordinated with a controller, with the ultimate goal of delivering the generated electrical energy to the grid for use.