How to easily solve the problem of inverter reporting overvoltage and unable to generate electricity when connected to the grid

According to safety regulations, grid-connected inverters must operate within the specified grid voltage range and be able to detect and synchronize with the grid voltage in real time. If the voltage value exceeds the safety regulations, the inverter must trip and stop working to ensure the safety of equipment and operators.

Fault Analysis 1

The cable between the inverter and the grid connection point is too thin, too long, entangled, or the cable material is unqualified, resulting in a voltage rise (?U increase) on the AC terminal side of the inverter, exceeding the grid connection voltage range set by the inverter safety regulations, and the inverter displays grid overvoltage; Solution:

1. Select AC cables with appropriate specifications and diameters to connect to the grid and reduce line losses (please refer to the cable selection table); 2. Select the nearest point to connect to the grid, shorten the distance from the inverter to the grid point, and reduce line losses;


Fault Analysis 2

Multiple single-phase inverters are connected to the same live wire, causing voltage imbalance in the grid, resulting in grid voltage increase and inverter overvoltage display.

Solution: Choose multi-point grid connection and distribute multiple inverters to the three phases of the grid.

Fault Analysis 3

The installed capacity of the photovoltaic system in the same substation is too large, and there are too many grid-connected power stations, resulting in insufficient load absorption capacity of the power grid, causing the grid voltage to rise and overvoltage reporting.

Solution: With the owner's consent, the inverter overvoltage load reduction method can be used to prevent the inverter from being disconnected from the grid.

Inverter AC Cable Selection

Wire diameter principle: The AC line loss between the inverter and the grid connection point shall not exceed 2% of the inverter output voltage; AC cables are generally YJV type cables; in engineering applications, the empirical formula can be used: △U=（I*L*2）/（r*S）△U cable voltage drop (V)

I: Maximum current the cable needs to withstand (A)

L: Cable laying length/m

S: Cable cross-sectional area/mm?

r: Conductor conductivity - m/(Ω*mm2), r copper = 57, r aluminum = 34 Aluminum wire selection: When aluminum wire is selected for AC output wire, the corresponding cross-sectional area Slv of the aluminum wire is required to be 1.5~2 times the cross-sectional area Scu of the copper wire;