How to choose an inverter? How to match photovoltaic inverters with components?

Choosing an inverter requires calculation: the maximum output current of the battery array should be less than the maximum input current of the inverter. In order to reduce the DC loss in the process from the component to the inverter, and to prevent the inverter from overheating or electrical damage caused by excessive current, the difference between the maximum input current value of the inverter and the current value of the battery array should be as large as possible. Efficiency marking is generally divided into maximum efficiency and European efficiency, and the European efficiency corrected by the weighted coefficient is more scientific. When other conditions are met, the conversion efficiency of the inverter should be as high as possible.

The inverter is an important component, and the equipment related to it is mainly the distribution cabinet and the monitoring system. The monitoring system of the grid-connected power station includes hardware and software, which needs to be tailored according to its own characteristics. Generally, large inverter manufacturers have developed a monitoring system specifically for their own inverters. Therefore, in the process of selecting the inverter, it is necessary to consider whether the relevant supporting equipment is complete.

One of the key factors in selecting an inverter is efficient power generation. To achieve efficient power generation in a photovoltaic power station, one indicator is the conversion efficiency of the inverter. The inverters that are often seen have two concepts: maximum efficiency and weighted efficiency. What is the difference between these two concepts? Greater efficiency means better performance of the inverter under better conditions. Weighted efficiency is the comprehensive performance of the inverter. The inverter can achieve efficient power generation as a comprehensive reflection. In this way, weighted efficiency is more meaningful for manufacturing.

Another key indicator is MPPT efficiency, which has two strategies: dynamic and static. At present, the algorithm of static MPPT efficiency is not a big problem and most manufacturers can achieve it. The key is dynamic MPPT efficiency. In the actual working environment of the inverter, conditions such as light and temperature are constantly changing. The two indicators of inverter conversion efficiency and MPPT efficiency will affect the power generation of the inverter, which can extend the power generation time and thus increase the power generation.

All of these depend on the roof situation. For home roofs or courtyards, with small installed capacity, single-phase or three-phase grid-connected string inverters are generally selected. When the roof area is too large, three-phase inverters are selected. For industrial and commercial roofs, complex mountainous areas and greenhouse projects, three-phase string inverters are generally selected for scenes with irregular orientations, prone to local shading, large installed capacity, and low or medium voltage grid-connected voltages. For large ground and desert power stations in the northwest region, it is recommended to use centralized box inverters. For the selection of inverters, the inverters of the corresponding power range are generally configured according to the requirements of the system. The power of the selected inverter should match the strongest power of the photovoltaic cell array. Generally, the rated output power of the photovoltaic inverter is selected to be close to the total input power, which can save costs.