DC to AC
Solar panels generate DC power, while the public power grid and most household appliances use AC power. The core function of the inverter is to convert the DC power output by the solar panel into AC power that meets the requirements of the public power grid, realize the connection between the solar power generation system and the power grid, and enable the generated electricity to be smoothly integrated into the power grid or used by household and commercial users.
For example, in a household grid-connected solar power generation system, the inverter converts the DC power generated by the solar panel during the day into 220V AC power to meet the power needs of household appliances such as televisions, refrigerators, and air conditioners.
Influence on system performance
Efficiency: The efficiency of the inverter directly affects the overall efficiency of the solar power generation system. An efficient inverter can minimize the loss in the energy conversion process and increase the output of electrical energy. For example, a high-efficiency inverter can convert the electricity generated by the solar panel into AC power with less loss, thereby increasing the power generation of the system and improving energy utilization efficiency.
Stability: Stable output voltage and frequency are essential to ensure the stable operation of the solar power generation system. The inverter needs to keep the voltage and frequency of the output AC power stable within the specified range under different lighting conditions and load changes to ensure the normal operation of the connected electrical equipment while avoiding interference with the public power grid.
Reliability: As one of the key equipment in the solar power generation system, the reliability of the inverter is directly related to the reliability of the entire system. A reliable inverter should be able to operate stably for a long time under various harsh environmental conditions, reduce the probability of failure, and reduce maintenance costs.
2. Key features
Efficient conversion
Adopt advanced power electronics technology, such as efficient power semiconductor devices (such as IGBT, MOSFET, etc.) and optimized circuit design to improve energy conversion efficiency. For example, the conversion efficiency of some high-end inverters can reach more than 98%, minimizing the loss of electric energy during the conversion process.
With intelligent MPPT (maximum power point tracking) function, it can track the maximum power point of the solar panel in real time to ensure that the solar panel always outputs electric energy at maximum power. MPPT technology can automatically adjust the working point of the inverter according to changes in light intensity and temperature to improve the power generation efficiency of the system.
Stable output
Output stable AC voltage and frequency, usually requiring the output voltage to meet the standards of the public power grid (such as 220V/380V) and the frequency to be 50Hz or 60Hz. The inverter monitors the output voltage and frequency in real time through precise control algorithms and feedback mechanisms, and makes adjustments to ensure stable power output under different load conditions.
It has good load adaptability and can operate stably under different load powers. Whether it is light load or heavy load, the inverter should be able to maintain the stability of the output voltage and frequency to avoid damage to electrical equipment or system failure due to load changes.
Safe and reliable
It has complete protection functions such as overvoltage protection, overcurrent protection, short circuit protection, overheating protection, etc. When the system is abnormal, the inverter can quickly cut off the circuit to protect the solar panels, the inverter itself and the connected electrical equipment from damage. For example, in the event of a grid failure or short circuit, the inverter should be able to automatically cut off the connection with the grid to prevent the current from flowing back into the solar panel and causing equipment damage.
It complies with relevant safety standards and certification requirements, such as international standards such as IEC and UL. These standards have strict regulations on the electrical safety, electromagnetic compatibility, and environmental adaptability of the inverter to ensure the safety and reliability of the inverter during use.
Have a good heat dissipation design to ensure that the inverter will not be damaged due to overheating during long-term operation. The inverter usually uses heat sinks, fans and other heat dissipation methods to dissipate the internal heat in time and keep the equipment within the normal operating temperature range.
III. Types and application scenarios
Centralized inverter
Features: Usually suitable for large photovoltaic power stations with large power, generally above several hundred kilowatts to megawatts. The centralized inverter connects multiple solar panels in series and parallel, and then connects to the grid after centralized inversion. It has the advantages of relatively low cost, high efficiency, and easy centralized management.
Application scenarios: large ground photovoltaic power stations, large industrial and commercial rooftop photovoltaic projects, etc. For example, in a large photovoltaic power station of 100MW, dozens of centralized inverters are used to convert the DC power generated by a large number of solar panels into AC power and then connect it to the grid.
String inverter
Features: Suitable for small and medium-sized photovoltaic power stations and distributed photovoltaic power generation systems. The string inverter combines multiple solar panels into a string, and each string is connected to an inverter for independent inversion. It has the advantages of high flexibility, high MPPT accuracy, and easy installation and maintenance.
Application scenarios: household rooftop photovoltaic power generation, small industrial and commercial rooftop photovoltaic projects, distributed photovoltaic poverty alleviation projects, etc. For example, in a household rooftop photovoltaic power generation system, several string inverters are used to convert the DC power generated by solar panels with different orientations and angles into AC power to meet the household electricity needs.
Micro inverter
Features: Mainly used for the inversion of a single solar panel, with low power, generally below a few hundred watts. The micro inverter is directly installed on the back or side of the solar panel to achieve independent inversion of each panel. It has the advantages of extremely high MPPT accuracy, high safety, and flexible installation.
Application scenarios: household rooftop photovoltaic power generation with high power generation requirements, small commercial building photovoltaic projects, etc. For example, in a rooftop photovoltaic power generation system of a high-end villa, multiple micro inverters are used to invert each solar panel separately to improve the overall power generation and reliability of the system.