Photovoltaic inverter selection technology analysis

Photovoltaic inverter is an inverter specially used in the field of solar photovoltaic power generation. It is one of the indispensable core components in the photovoltaic system. Its biggest function is to convert the direct current generated by solar cells into alternating current energy that can be directly connected to the power grid and load through power electronics technology.

Photovoltaic inverters can be divided into centralized inverters, string inverters and micro inverters according to their application scenarios. Centralized inverters have the advantages of easy management, high reliability, high power quality, complete protection functions, high power station safety, strong power regulation and low voltage ride-through capabilities, and good grid regulation. However, they also have disadvantages such as relatively poor component configuration flexibility, fire risk of built-in DC fuses, easy overload or underload, mismatch or overmatch, long maintenance period, and great impact on power generation.

The advantages of string inverters are simple networking structure, flexible distribution, full utilization of irregular areas, little impact of component inconsistency on power generation, simple operation and maintenance, etc. Its disadvantages are many electronic components, slightly poor reliability, easy aging of the casing and heat sink due to wind and sun, large DC component, high total failure rate with serious consequences, poor zero voltage ride-through capability, and easy to make wrong connections, reverse connections, loose connections, and false connections during construction.

The micro inverter connects each photovoltaic module to an inverter, and each module has a separate MPPT tracking. Its advantages are simple installation, investment savings, no DC part design and DC loss, no DC high voltage, and high system safety and stability. Its disadvantages are high cost and high operation and maintenance costs.

Based on the above analysis, we can see that the three inverters have their own advantages and disadvantages. Photovoltaic investors should adhere to the design concept of "adapting measures to local conditions and scientific design". Different types of photovoltaic inverters should be selected for different application locations. For example, for large ground power stations, centralized inverters are recommended; for mountain photovoltaic power stations, multi-channel MPPT centralized inverters should be used, and some power stations with small content and complex terrain should use string inverters; for rooftop photovoltaic power stations with larger capacity, string inverters are recommended, and household rooftop photovoltaics can use micro inverters. For plain photovoltaic power stations, when the investment cost is close, this article recommends that centralized inverters or string inverters can be used according to actual conditions.