Composition of Photovoltaic Power Generation Systems
Photovoltaic power generation systems, also known as solar energy systems, have emerged as a promising solution to the world's growing energy demands. These systems harness the power of sunlight and convert it into electricity using photovoltaic cells. This renewable energy source offers numerous advantages over traditional forms of power generation. Unlike fossil fuel-based power plants, solar energy does not release harmful greenhouse gases or pollutants into the atmosphere. This makes it an ideal choice for combating climate change and reducing air pollution. Additionally, photovoltaic power generation systems are highly sustainable. The sun is an abundant and inexhaustible source of energy, ensuring that solar panels can generate electricity for decades without depleting natural resources. Moreover, these systems require minimal maintenance once installed, making them cost-effective in the long run. Furthermore, photovoltaic power generation systems can be deployed in various settings. From residential rooftops to large-scale solar farms, this technology is versatile and adaptable to different environments. It can even be integrated into buildings' architecture through innovative designs.
 
Photovoltaic power generation refers to direct power generation that uses photovoltaic cell arrays to convert solar radiation energy into electrical energy. The photovoltaic power generation system is a power generation and electric energy conversion system composed of photovoltaic cell arrays, controllers, and electric energy storage and conversion links. The electric energy generated by the photovoltaic cell array is stored and converted through cables, controllers, energy storage and other links, and converted into electric energy that can be used by the load.
 
1. Solar cell arrays
The solar cell is the smallest unit of photoelectric conversion. Its working voltage is about 0.45 to 0.5V, which is far lower than the actual required voltage. Generally, it cannot be used as a power source alone. To meet the needs of practical applications, solar cell units are connected in series and packaged to become solar cell modules. Its power is generally from a few watts to tens of watts or more than a hundred watts. It is the smallest unit that can be used as a power source alone. The solar cell modules are connected in series and parallel and mounted on the bracket to form a solar cell array, which can meet the output power required by the load.
 
2. Anti-reverse charging diodes
The function of the anti-reverse charging diode is to prevent the battery pack from discharging through the solar cell array when the solar cell array does not generate electricity or has a short circuit due to insufficient sunlight on rainy days and nights. It is connected in series in the solar cell array circuit and plays a one-way conduction role.
 
3. Battery packs
The function of the battery pack is to store the electrical energy emitted by the solar cell array when it is exposed to light and to provide power to the load at any time. Batteries are key components in photovoltaic power generation. Failures and short service life of batteries are also some of the main reasons that hinder the expansion of independent photovoltaic power generation systems. At present, most of the batteries used in photovoltaic power generation systems in China are lead-acid batteries, and there are also a small number of systems used in high-cold outdoor systems that use cadmium-nickel batteries.
 
4. Controllers
A controller is one of the core components of the photovoltaic power generation system. The photovoltaic power generation system operates under the management of the controller. The controller of the photovoltaic power generation system should generally have the following functions:

Signal detection
Optimal charging control of the battery
Discharge management of the battery
Equipment protection
Diagnosis and positioning of the fault
Indication of the operating status indication: The controller can adopt a variety of technical methods to realize its control. The more common methods are logic control and computer control.
 
5. Inverters
An inverter is a device that converts direct current into alternating current. Since solar cells and batteries emit direct current, an inverter is indispensable when the load is alternating current. According to its operating mode, it can be divided into independent operating inverter and grid-connected inverter. The former is used for independently operating solar cell power generation systems to supply power to independent loads, while the latter is used for grid-connected solar cell power generation systems to feed the generated power into the grid.
 
6. Measuring equipment
For industrial power systems such as solar communication power systems and medium and large-scale solar photovoltaic power stations, it is often required to measure a large number of parameters, such as solar radiation, ambient temperature, etc. Some even require remote data input, and remote control. This requires the solar cell power generation system to be equipped with a data acquisition system and a microcomputer monitoring system.
 
7. Maximum power point tracking (MPPT)
The output of the solar cell array changes with the solar irradiance and the surface temperature of the solar cell array. Therefore, it is necessary to track the working point of the solar cell array and control it so that the array is always at maximum output to obtain maximum power output.