What Is A PV Inverter?

The downstream of the energy storage industry can be divided into three major areas: power supply side, grid side, and user side. Among them, power side applications include scenarios such as joint frequency regulation of thermal power units and grid connection of renewable energy (i.e. new energy distribution and storage); The grid side field includes scenarios such as independent energy storage and substation energy storage. Energy storage systems are used to optimize the grid structure, participate in grid peak shaving and frequency regulation, and improve power quality; The user side is mainly used for spontaneous self use of electricity, peak valley price arbitrage, capacity electricity fee management, and improving power supply reliability.

According to data disclosed by the General Administration of Customs, China's inverter exports reached 9.954 billion US dollars in 2023, an increase of 11.37% compared to 8.938 billion US dollars in 2022. Throughout the year, a total of 51.28 million inverters were exported, a year-on-year increase of 2%. The weight of inverter exports was 333600 tons, a year-on-year increase of 9.8%.Inverter, also known as power regulator or power regulator, usually refers to the process of physically converting DC electrical energy into AC electrical energy as inverter, and the device that implements the inverter process is called inverter equipment or inverter. Inverters used in photovoltaic power generation systems are generally referred to as "photovoltaic inverters".

Photovoltaic inverters convert the variable DC voltage generated by solar photovoltaic modules into AC power at the mains frequency, which can be connected to the public power grid transmission system or used for off grid power grids. They are an essential part of photovoltaic systems. Known as the "brain" or "heart" of photovoltaic power generation systems.

Photovoltaic inverters mainly consist of logic control circuits, filtering circuits, and inverter circuits, with the inverter circuit being the core of the inverter. Photovoltaic inverters are divided into centralized inverters, string inverters, distributed inverters, and micro inverters according to their technical routes.

What is a centralized inverter?

Centralized inverter is converging and then inverting, it converges multiple parallel strings to DC input first, and then converts them to AC power centrally after maximum power peak tracking, usually the single capacity is over 500 MW.

The centralized inverter system is highly integrated and has high power density, and the power is gradually increased from the initial 500 kW to 630 kW, 1.25 MW, 2.5 MW, 3.125 MW, 3.3 MW, 4.4 MW and so on. Centralized inverters are mainly applied to centralized ground-based large-scale PV power stations with uniform light, such as mountain, desert, water surface and other scenarios.

What is string inverter?

String inverter first inverts and then converges, it is based on the concept of modularization, after individual maximum power peak tracking of 1-4 groups of PV strings, it first inverts the DC power it generates into AC power, and then converges and boosts it, and then connects it to the grid.

At present, the power of string-type small power inverter is generally between 1 kW and 80 kW, and the mainstream power of string-type high power inverter has reached 250-350 kW. String inverters have the advantages of large number of MPPTs with high tracking accuracy, high power generation, flexible component configuration, easy installation, and fast operation and maintenance.

String inverters have rich application scenarios and can be used in centralized power plants, distributed power plants, small and medium-sized rooftop power plants and other types of power plants.

What is a distributed inverter?

A hub-and-spoke inverter realizes multiple MPPT optimization functions by front-loading multiple MPPT control optimizers, which are converged and inverted by a centralized inverter.

The decentralized inverter combines the advantages of the centralized inverter and the string inverter, and achieves the low cost and high reliability of the centralized inverter and the high power generation of the string inverter.

Centralized inverters are mainly used in centralized ground-based large-scale PV power plants, such as mountain, desert, water and other scenarios.

What is a micro inverter?

Micro inverter, is a separate maximum power peak tracking for each PV module, and then inverted and integrated into the AC grid. Compared to centralized, string inverters and hub-and-spoke inverters, micro inverters are the smallest in size and the smallest in power, with a general power of less than 1 kW.

The advantage of micro inverter is that it can track and control the maximum power of each module independently, which can improve the overall efficiency of the system in case of shading or difference in the performance of the modules, and at the same time, it can guarantee the safety of the power station to the greatest extent.

Microinverters are mainly suitable for balcony PV and small distributed industrial and commercial rooftop power plants.