
On Multi-angle, multi-directional roof
According to the basic principle of circuit series, in the same loop, the current is determined by the smallest component, which is the well-known principle of the barrel effect. Therefore, when designing the strings, the component model, installation angle, and number of strings of each loop of each inverter should be kept as consistent as possible. Each MPPT loop of the inverter runs independently and does not interfere with each other, so different MPPT loops can be different.
When facing a roof with a complex structure, you can select multiple inverters or multiple MPPT inverters based on the number of locally consistent components. At present, the inverter technology is very mature, and the harmonic suppression problem of multiple inverters in parallel has been solved. Inverters of different powers are combined together on the grid side without any problems. In projects with larger photovoltaic power, you can choose an inverter with high single-unit power and multiple MPPTs to further reduce the series-parallel mismatch loss of modules under complex roof conditions.
In some more complex scenarios, three-phase grid-connected and single-phase grid-connected may occur at the same time. At this time, three-phase inverters and single-phase inverters can also be combined. According to the current national standard "Design Specification for Low-Voltage Power Distribution", there are three forms of low-voltage power distribution systems, namely IT systems, TT systems, and TN systems. Among them, the IT system does not have a neutral line, and the TT system and TN system have a neutral line. In the industrial, commercial and civil systems, most of them are TN systems. The grid-connected inverter is connected to the grid, the three-phase inverter is three-phase five-wire, and the single-phase inverter is a live wire, a neutral wire and a ground wire. Therefore, when there are three-phase and single-phase, they are connected to the grid. In the scenario, there is no problem with the electrical connection.
★Note: When single-phase inverters are connected to the three-phase power grid, pay attention to the problem of three-phase unbalance. Therefore, try to connect the single-phase inverter to the phase with the largest load. If it is a single-phase inverter, Try to evenly distribute and connect to the three phases.