What are the types of photovoltaic inverters? What are their advantages and disadvantages?

What is an inverter? Inverters play an important role in photovoltaic power generation. They mainly convert the direct current generated by photovoltaic modules into alternating current. Therefore, many people call them "photovoltaic inverters". Since most people know too little about photovoltaic inverters, they don't know what types of photovoltaic inverters there are. Don't worry, the editor will give you a popular science of photovoltaic inverter types and their advantages and disadvantages.

There are three main types of photovoltaic inverters: centralized inverters, string inverters and distributed inverters. These three types of inverters are more common in the market, and their advantages and disadvantages are also different.

1. Centralized inverter

Centralized inverters, as the name implies, convert the DC power generated by photovoltaic modules into AC power, then boost the voltage and connect it to the grid. Therefore, the power of the inverter is relatively large. Centralized inverters with a capacity of more than 500kW are generally used in photovoltaic power stations.

Advantages of centralized photovoltaic inverters:

1. High power, small quantity, easy to manage; few components, good stability, easy to maintain;

2. Low harmonic content, high power quality; complete protection functions and high safety;

3. It has power factor regulation function and low voltage ride-through function, and the grid regulation is good.

Disadvantages of centralized photovoltaic inverters:

1. The MPPT voltage range of the centralized inverter is narrow, and the operation of each component cannot be monitored. Therefore, it is impossible to make each component at the optimal working point, and the component configuration is not flexible;

2. Centralized inverters occupy a large area, require a dedicated machine room, and are inflexible to install;

3. The power consumption of the equipment room itself and the ventilation and heat dissipation of the equipment room are high.

2. String Inverter

As the name implies, string inverters convert the DC power generated by photovoltaic modules directly into AC power, which is then aggregated and boosted for grid connection. Therefore, the power of the inverter is relatively small. String inverters with a power of less than 50kW are generally used in photovoltaic power stations.

Advantages of string photovoltaic inverters:

1. It is not affected by module differences between strings and shadows, and reduces the mismatch between the optimal working point of the photovoltaic cell module and the inverter, thus maximizing the power generation;

2. The MPPT voltage range is wide, and the component configuration is more flexible; on rainy days and in foggy areas, the power generation time is long;

3. Small size, small footprint, no need for a dedicated machine room, flexible installation;

4. Low power consumption and small impact of failure.

Disadvantages of string photovoltaic inverters:

1. The electrical clearance of power devices is small, which is not suitable for high altitude areas; there are many components, which are integrated together and have slightly poor stability;

2. Outdoor installation, wind and sun can easily cause aging of the shell and heat sink;

3. If there are many inverters, the total failure rate will increase, and system monitoring will be difficult;

4. It is designed without isolation transformer, so the electrical safety is slightly poor and it is not suitable for the negative grounding system of thin-film modules.

3. Distributed Inverter

Distributed inverter is a new inverter type proposed in the past two years. Its main features are "centralized inverter" and "distributed MPPT tracking". Distributed inverter is a product that gathers the advantages of both centralized inverter and string inverter, achieving "low cost of centralized inverter and high power generation of string inverter".

Advantages of distributed photovoltaic inverters:

1. Compared with centralized tracking, “decentralized MPPT tracking” reduces the probability of mismatch and increases power generation;

2. Compared with centralized and string inverters, distributed inverters have a voltage boost function, which reduces line losses;

3. Compared with the string type, "centralized inverter" has more advantages in construction cost.

Disadvantages of distributed photovoltaic inverters:

1. Little engineering experience. Compared with the first two categories, it is still a new form and has relatively few applications in engineering projects;

2. Safety, stability, high power generation and other characteristics still need to be tested by engineering projects;

3. Because of the use of "centralized inversion", the disadvantages of occupying a large area and requiring a dedicated machine room also exist in distributed inverters.

The above is an introduction to the types of photovoltaic inverters and their respective advantages and disadvantages. If you have read this article carefully, I believe it will be of great help to you in purchasing photovoltaic inverters. The more you know about photovoltaic inverters, the more comfortable you will be when purchasing.