Comparison of four photovoltaic system power generation grid-connected schemes:
The centralized grid connection method is suitable for installing solar cell arrays of the same orientation and the same specifications. In the electrical design, a single inverter is used to realize a centralized grid-connected power generation solution. For large-scale grid-connected photovoltaic systems, if the orientation, inclination and shadow of the solar cell array are basically the same, a large centralized three-phase inverter is usually used. The main advantage of this method is that photovoltaic grid-connected is used in the overall structure. There are fewer inverters and simple installation and construction; the centralized inverter used has high power and high efficiency. The main disadvantage of this method is that once the grid-connected inverter fails, a large-area solar photovoltaic system will be deactivated.steel z profile
2. string type
Photovoltaic grid-connected string inverters connect each PV module to an inverter, and each PV module has a separate maximum power peak tracking, so that the photovoltaic system battery components and the inverter are better. . String inverters have become the most popular inverters on the international market. The string inverters are based on the modular concept. Each PV string (1kW ~ 5kW) passes through an inverter in DC. The terminal has maximum power peak tracking and is connected in parallel to the AC terminal. Many large-scale photovoltaic valve power plants use string inverters, which have the advantage of being unaffected by differences and shading between photovoltaic cell strings.
For the large-scale photovoltaic power generation system, the master-slave structure can be adopted, and the master-slave structure is actually a centralized type. The main feature of the structure is that two to three centralized inverters are used, and the total power is divided by several inverters. . When the radiation is low, only one inverter works to increase the efficiency of the inverter in the solar cell array and output low power; when the solar radiation rises, the solar cell array output power increases to more than one. When the capacity of the inverter is reached, the other inverter is automatically put into operation. In order to ensure that the running time of the inverter is equal, the master-slave inverter can automatically rotate the master-slave configuration. The initial cost of the master-slave structure will be relatively high, but it can improve the efficiency of the photovoltaic system inverter operation. For large-scale photovoltaic systems, the efficiency can produce greater economic benefits.
Distributed grid-connected power generation is suitable for installing solar cells in different orientations or different specifications. In the electrical design, the square array of solar cells with the same orientation and the same specifications can be integrated and connected to the grid for power generation through a single inverter. The large distributed system is mainly for the orientation, inclination and sun shadow of the solar cell array. The situation used. The distributed system serializes the same orientation, inclination and shadowless photovoltaic modules into a series, consisting of a string or strings of a solar cell array, and a grid-connected inverter is matched. In this case, the junction box can be omitted to reduce the cost; the grid-connected photovoltaic system can also be repaired in pieces to reduce the power generation loss during maintenance.