Inverters also have several other important functions. For example, they can control the power output of the entire photovoltaic system, dynamically adjust the output power curve of the solar photovoltaic cells, achieve maximum power point tracking control, and ultimately convert the DC power generated by the photovoltaic cells into AC power for grid connection. The performance of the inverter is crucial for improving system efficiency, reliability, and reducing costs. Therefore, selecting the right inverter type for the application is essential. Depending on the classification method, solar inverters come in various types, including but not limited to square wave inverters, stepped wave inverters, sine wave inverters, power frequency inverters, high-frequency inverters, single-phase inverters, and three-phase inverters.
There are also inverters for specific applications, such as grid-connected inverters for grid-connected power generation and small inverters for stand-alone operation. When selecting an inverter, factors such as its application, capacity, output waveform, efficiency, and reliability need to be considered. Solar inverters are one of the key devices for achieving efficient and stable operation of solar power systems, and are of great significance for promoting and applying renewable energy sources such as solar energy.
The following is a classification of solar inverters:
Classification by output waveform:
Square wave inverter: The output AC voltage waveform is a square wave. This type of inverter uses relatively simple inverter circuitry and a smaller number of power switching transistors. The design power is generally between hundreds of watts and kilowatts.
Stepped-wave inverters: The output AC voltage waveform is a stepped wave. There are various types of these inverters with different circuits, resulting in a wide variation in the number of steps in the output waveform. This poses challenges for the grouping and wiring of solar cell arrays and for the equalization charging of batteries. Furthermore, stepped-wave voltage still causes some high-frequency interference to radios and certain communication devices.
Sine wave inverter: The output AC voltage waveform is a sine wave.
Classification by output AC power frequency:
Industrial frequency inverter: An inverter with a frequency of 50-60Hz.
Medium frequency inverters: The frequency is generally from 400Hz to tens of kHz.
High-frequency inverters: The frequency is typically from tens of kHz to MHz.
Inverter can be classified according to the number of phases output:
Single-phase inverters are suitable for small systems with low load power or single-phase loads.
Three-phase inverter: suitable for medium to large systems or loads that require three-phase power supply.
Multiphase inverters: suitable for large systems or high-load applications that require multiphase power.
Classified by system capacity:
Low-power inverters: The output power is generally below 100W, suitable for small-capacity load applications, such as personal use or small commercial applications.
Medium-power inverters: The output power is generally between 100W and several kilowatts, suitable for medium-capacity loads such as small factories, offices, and homes.
High-power inverters: The output power is generally between several kilowatts and tens of kilowatts, and they are suitable for large-capacity load applications, such as large factories, shopping malls, and data centers.
Classified by application:
Grid-connected inverters: These are used to connect solar power systems to the power grid, enabling grid-connected power generation. This type of inverter needs to be synchronized with the grid and has corresponding control and protection functions.
Stand-alone inverters: These are used in small-scale solar power systems that are not connected to the grid, such as for residential or small commercial applications. This type of inverter needs to be able to operate independently and has functions such as energy storage and load control.
Classified by structure:
String inverters: They first invert and then combine current, and are mainly suitable for small to medium-sized rooftop and ground-mounted power stations. They have a wider range of applications, suitable for centralized power stations, distributed power stations, and rooftop power stations, and are slightly more expensive than centralized inverters.
Centralized inverters: These inverters combine current first and then invert it, and are mainly suitable for large-scale centralized power plant scenarios with uniform sunlight. Due to their low cost, they are primarily used in large-scale centralized photovoltaic power plants such as large factories and desert power plants with uniform sunlight.
Micro inverters: Direct inverters for grid connection, primarily suitable for residential and small-scale distributed applications. They typically have a power output below 1kW and are mainly used in distributed residential and small-scale distributed commercial and industrial rooftop power stations, but they are expensive and difficult to maintain in case of failure.
The above are the classification methods for solar inverters. Different classification methods cover different application scenarios and needs. Choosing the right inverter type is crucial for the stable and efficient operation of a solar power generation system.
