Failure Analysis of Solar Inverter

10kW hybrid solar inverterLow insulation resistance

Unplug all the strings on the input side of the solar inverter, and then connect them one by one. Use the function of the solar inverter to start up to detect the insulation resistance to detect the faulty strings. After finding the faulty strings, check whether the DC connectors are flooded with short-circuit brackets. Or burn the short-circuit bracket, and also check whether the component itself has black spots on the edge to burn, causing the component to leak to the ground grid through the frame.

Low bus voltage

If it occurs in the morning or evening period, it is a normal problem, because the solar inverter is trying to limit the power generation conditions. If it occurs in normal daytime, the detection method is still the exclusion method, and the detection method is the same as said above.

Leakage current fault

If the leakage current is too large, remove the input terminal of the PV array, then check the peripheral AC power grid, disconnect the DC terminal and the AC terminal, and let the solar inverter power off for 30 minutes. To contact a professional engineer.

DC overvoltage protection

With the pursuit of high-efficiency process improvement of components, the power level is constantly updated and increased, and the open-circuit voltage and operating voltage of components are also rising. The temperature coefficient problem must be considered in the design stage to avoid hard damage to the equipment caused by overvoltage at low temperature.

No response to inverter startup

Please make sure that the DC input line is not reversed. Generally, the DC connector has a foolproof effect, but the crimping terminal has no foolproof effect. It is very important to read the solar inverter manual carefully to ensure that the positive and negative poles are crimped. The inverter has built-in reverse short-circuit protection, and starts normally after the normal wiring is restored.

Grid failure

It is very important to investigate the heavy load and light load of the power grid in the early stage. The main reason for grid overvoltage problems is that the light load voltage of the original grid exceeds or is close to the safety protection value. If the grid tie line is too long or the crimping is not good, the line impedance/inductive reactance is too large, and the power station cannot operate normally and stably.

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