Therefore, when the inverter reports system fault information, people often feel helpless. Understanding troubleshooting tips for inverter malfunctions is therefore crucial for ensuring the inverter functions properly.
In principle, photovoltaic inverters themselves do not generate voltage. The voltage displayed by the inverter comes partly from the photovoltaic modules (DC voltage) and partly from the grid (AC voltage). So, how should you handle a "grid-connected inverter displaying AC overvoltage" problem? There are essentially three scenarios when an inverter experiences AC overvoltage:
1. The grid connection distance is too far, causing voltage rise.
If the distance between the grid-connected inverter and the grid connection point is too far, the voltage difference on the AC terminal side of the inverter will increase. When this voltage exceeds the inverter's specified grid connection voltage range, the inverter will display a grid overvoltage warning. Additionally, if the cables used to connect the inverter to the grid connection point are too long, too thin, tangled, or made of non-compliant materials, they will also increase the voltage difference on the inverter's AC terminal. Therefore, cable selection and proper cable layout are particularly important.
In this situation, the first step is to check whether the grid connection distance is too long, and it is best to choose a solution that connects to the grid nearby; secondly, check the cable distribution and cable quality, and choose a reasonable wiring method and qualified AC cables.
II. Multiple inverters connected to one access point
Photovoltaic power generation in China is a relatively recent phenomenon, and power supply bureaus lack experience in selecting inverters for grid connection, sometimes exhibiting unprofessional or ill-considered approaches. A common problem is connecting multiple single-phase inverters to the same phase, which easily leads to grid voltage imbalance and a rise in grid voltage, resulting in excessively high grid connection voltage.
This situation is relatively easy to solve. It requires considering distributing the project's grid-connected capacity across the three phases of the power grid and selecting multiple grid connection points.
3. Excessive photovoltaic installed capacity in the same distribution area
With increasingly favorable national policies and expanded financing channels for photovoltaic (PV) systems, many people are rushing to install them. This could lead to a situation where there is too much PV installation capacity within the same area (the power supply range of a single transformer), while the grid's load capacity is insufficient. Since the electricity generated by the PV system cannot be consumed locally or transmitted over long distances, the grid voltage will naturally rise continuously, causing the inverter to display an excessively high grid voltage.
The solutions to this situation are: 1. Reduce the capacity of the photovoltaic power station; 2. Increase the capacity of the transformer; 3. Take preventative measures: conduct preliminary surveys of the power grid to assess the appropriate grid connection capacity (the best approach).
According to relevant regulations, photovoltaic grid-connected inverters must operate within the specified grid voltage range, be able to monitor and synchronize with the grid voltage in real time, and when the inverter detects that the grid voltage (AC voltage) exceeds the specified range, the inverter must trip and stop working in order to ensure equipment safety and protect the personal safety of operators.
