Instructions for quickly handling common problems of hybrid systems

With the increasing trend towards using green energy for living and production purposes, the number of solar photovoltaic (PV) systems in Vietnam is growing rapidly. Thousands of grid-tied (On-Grid) and hybrid solar PV systems have been installed and put into operation, helping users save on electricity costs and contribute to reducing CO2 emissions.

Among them, hybrid systems can store surplus solar energy during the day for use in the evening or during power outages. They also provide continuous, stable power for essential electrical devices such as surveillance cameras, refrigerators, freezers, computer systems, Wi-Fi, fire alarm systems, garage doors, and Koi ponds. Therefore, many Vietnamese households are considering installing hybrid systems to meet their energy needs.

However, for optimal operation and high efficiency of hybrid systems, users need to understand the operating principles and how to quickly address common issues.

1. Key components of a hybrid PV system:

Main components of a Hybrid solar power system

2. Common issues and troubleshooting procedures when the system fails:

During operation, users may encounter situations where the PV system fails to generate electricity. Before troubleshooting the system, it’s essential for the troubleshooter to have technical expertise and a good understanding of the system. Refer to the product user manual or contact the supplier or dealer for support.

a) Grid loss error:

– Causes:

• Grid power outage.
• MCB or MCCB supplying power to the inverter is off or faulty.

– Troubleshooting:

• Check if there is voltage at the MCB or MCCB supplying power to the inverter. The inverter will automatically restore and operate normally once grid voltage returns to normal.
• Check if the MCB or MCCB is faulty. Replace with a similar-rated MCB or MCCB if necessary.
• Investigate the reason why the MCB tripped.

b) Grid voltage error (overvoltage or undervoltage):

– Causes:

• Grid voltage is outside the allowable range for the inverter.

– Troubleshooting:

• Check the grid voltage at the inverter connection point to ensure it is within the allowable range. The inverter will resume operation once the grid voltage returns to the inverter’s operating range.
• Adjust the inverter’s voltage protection settings if needed to match the current grid voltage.
• Contact the local electricity provider to address cases of excessively high or low grid voltage.

c) Ground fault error:

– Causes:

• Inverter’s grounding cable is not connected securely.
• Grounding resistance is too high.

– Troubleshooting:

• Inspect the grounding cable for any disconnections or loose connections.
• Check the grounding resistance.

d) Backup output overload error:

– Causes:

• Load power consumption on the backup output exceeds the inverter’s backup output capacity.
• Use of high-starting current devices on the backup output, such as motors, water pumps, air conditioners, etc.

– Troubleshooting:

• Check the connected load: Ensure that the total power consumption does not exceed the backup output limit of the inverter. Verify if the connected loads are supported by the manufacturer.
• Review the inverter settings: Adjust settings if necessary to handle the current load.
• Inspect power cables and the automatic transfer switch (ATS) to ensure proper operation. If the load is too heavy, consider turning off some devices to reduce the load.

e) BMS communication error between inverter and battery:

– Causes:

• Communication cable between inverter and battery is broken, loose, or insecurely connected.
• Battery or inverter is faulty and not powering up.
• Incorrect BMS CAN or RS485 communication port connection.
• Incorrect communication cable used, not meeting standards.

– Troubleshooting:

• Check the communication cable: Ensure the cable between the inverter and BMS is not broken, loose, or insecurely connected.
• Verify communication settings: Check communication settings on both the inverter and BMS to ensure they use the same protocol and transmission speed.
• Check battery status: Ensure the battery is operational. Faulty batteries may prevent communication with the inverter.
• Restart the system after troubleshooting.

f) Low insulation resistance and leakage current error:

– Nguyên nhân:

• Dây cáp AC, DC lắp đặt trong môi trường ẩm ướt.
• Lớp vỏ cách điện của cáp AC, DC bị lão hóa hoặc bị xước làm giảm điện trở cách điện.

– Cách xử lý:

• Kiểm tra điện trở cách điện AC, DC bằng máy đo điện trở cách điện.
• Thay thế dây cáp AC, DC nếu lớp vỏ bảo vệ có dấu hiệu lão hóa hoặc bị xước.
• Kiểm tra lại thiết bị chóng sét lan truyền SPD AC và DC.

g) Lỗi quá điện áp DC BUS

– Causes:

• AC or DC cables installed in humid environments.
• Aging or scratched insulation layer of AC or DC cables causing reduced insulation resistance.

–  Troubleshooting:

• Measure the insulation resistance of AC or DC cables using appropriate testing equipment.
• Replace AC or DC cables if the protective insulation layer shows signs of aging or damage.
• Check surge protection devices (SPDs) for AC and DC circuits.

g) DC BUS overvoltage error:

– Causes:

Solar panel string voltage exceeds the inverter’s operating voltage range.

– Troubleshooting:

• Check the type, voltage rating of solar panels, and the number of panels per string. Ensure they are compatible with the inverter’s maximum operating voltage range.
• Restart the system after troubleshooting.

h) Smart Meter communication error:

– Causes:

• Communication cable between inverter and Smart Meter is broken, loose, or insecurely connected.
• Smart Meter or inverter is faulty and not powering up.
• Incorrect communication cable used.
• Incorrect communication settings on the Smart Meter.

– Troubleshooting:

• Check the communication cable: Ensure the cable between the inverter and Smart Meter is not broken, loose, or insecurely connected.
• Verify communication settings: Ensure correct communication settings on both the inverter and Smart Meter.
• Restart the system after troubleshooting.

i) Smart Meter / CT reverse error:

– Causes: