A summary of common photovoltaic "inverter" faults and solutions!

Generally, as long as the inverter is in the grid-connected state, the power curve displayed by the monitoring is a normal "mountain" line, which proves that the power station is running stably. If there is an abnormality, the health status of the power station's supporting equipment can be checked through the information fed back by the inverter. The following lists the basic problems and solutions:

Basic issues and solutions

1. Low insulation impedance: Use the elimination method. Unplug all the strings on the input side of the inverter, and then connect them one by one. Use the function of detecting insulation impedance when the inverter is turned on to detect the problematic strings. After finding the problematic strings, focus on checking whether the DC connector has a water-immersed short-circuit bracket or a burnt short-circuit bracket. In addition, you can also check whether there are black spots on the edges of the components themselves, causing the components to leak electricity through the frame to the ground grid.

2. Low bus voltage: If it occurs in the morning or evening, it is a normal problem because the inverter is trying to generate power at the limit. If it occurs during normal daytime, the detection method is still elimination method, and the detection method is the same as item 1.

3. Leakage current failure: The root cause of this type of problem is the installation quality problem, which is caused by choosing the wrong installation location and low-quality equipment. There are many fault points: low-quality DC connectors, low-quality components, unqualified component installation height, low-quality grid-connected equipment or water leakage. Once such problems occur, the fault point can be found by sprinkling powder and doing a good job of insulation. If it is a problem with the material itself, the material can only be replaced.

4. DC overvoltage protection: As components pursue high-efficiency process improvements, power levels are constantly updated and increased. At the same time, the open-circuit voltage and operating voltage of components are also increasing. The temperature coefficient issue must be considered during the design phase to avoid overvoltage in low temperature conditions, which may cause hardware damage to the equipment.

5. The inverter does not respond when it is turned on: Please make sure that the DC input line is not connected in reverse. It is important to read the inverter manual carefully to ensure the positive and negative poles before crimping. The inverter has built-in reverse short-circuit protection and will start normally after restoring normal wiring.

6. Grid failure:

Grid overvoltage: The work of preliminary investigation of grid heavy load (working time with high power consumption)/light load (rest time with low power consumption) is reflected here. Investigate the health of the voltage at the grid connection point in advance, communicate with the inverter manufacturer about the grid situation and combine the technology to ensure that the project design is within a reasonable range. Do not "take it for granted", especially in rural power grids. The inverter has strict requirements on grid connection voltage, grid connection waveform, and grid connection distance. Most of the reasons for grid overvoltage problems are that the original grid light load voltage exceeds or approaches the safety protection value. If the grid connection line is too long or the crimping is not good, resulting in excessive line impedance/inductance, the power station cannot operate normally and stably. The solution is to find the power supply bureau to coordinate the voltage or correctly select the grid connection and strictly control the quality of power station construction.

Grid undervoltage: The handling method for this problem is the same as that for grid overvoltage. However, if the voltage of an independent phase is too low, in addition to incomplete load distribution of the original grid, power failure or circuit breakage of the phase grid will also cause this problem, resulting in virtual voltage.

Grid over/under frequency: If this type of problem occurs in a normal power grid, it proves that the health of the power grid is very worrying.

There is no voltage in the grid: just check the grid-connected line.

The power grid is missing a phase: Check the missing phase circuit, that is, the line without voltage.

7. The last point - monitoring connection: correctly read the manual of each device, model line crimping, equipment connection, and set the communication address and time of the equipment to ensure stable and effective communication!

8. Power generation guarantee: When you have time, wipe the board and the power generation will increase immediately.

In fact, for a power station, many problems are not caused by the inverter itself, but are related to other equipment or installation methods. Therefore, the early material selection and installation also need our attention.

The design of the inclination and azimuth angles, the design of the spacing between components, the selection of the installation site, the health check of the grid voltage, and other preliminary work also determine the performance of the power station operation and power generation in the following 25 years. It can be said that the overall quality of the power station is determined by the quality of the materials and installation of the power station!

1. Components: Choose Grade A boards, and make decisions based on price. Reject low-priced and low-quality products, such as those with poor grid lines.

2. Bracket: Use anti-corrosion bracket, and the component should be at least 30cm above the ground.

3. Grounding flat steel: It is very important to correctly design and configure the grounding project according to the system size.

4. DC terminal: a very important material. Poor quality terminals will often overheat and melt due to single-point contact of the terminal core. Terminals with poor waterproofness will cause false short circuits and leakage between the terminal and the bracket on rainy days. The editor will not post the burning situation to leave some room for imagination.

5. DC cable: Choose the correct cable model and size. The design value should not be too small or too large, generally 1.2-1.5 times is enough. If it is too small, the current carrying capacity is insufficient, and if it is too large, the terminal crimping is poor. It is forbidden to "tie the wire" at will.

6. Inverter: Choose an inverter of high quality. Pay attention to heat dissipation when installing the inverter. Currently, inverters are all IP65 outdoor installations. It is recommended not to install them in narrow indoor places, especially for residential customers, to avoid heat dissipation problems and equipment operation noise problems. Reading the instructions correctly is the best choice.

7. AC cable: Choose the correct cable model and size. The design value should not be too small or too large, generally 1.2-1.5 times is enough. If it is too small, the current carrying capacity will be insufficient, and if it is too large, the terminal crimping will be poor.

8. Cable tray: A good power station always needs neat wiring. Whether it is a cable tray or a simple fixing method, it determines the beauty and durability of the power station.

9. AC grid-connected equipment: Avoid cutting corners, correctly select grid-connected switches and lightning protection equipment, and correctly design grid-connected lines to ensure reliable operation of the system.