With the strong support and promotion of the photovoltaic (PV) industry by the state, the number of household PV users is increasing, and PV construction is booming across various regions. As a veteran in the PV industry, I am often asked various questions about PV systems. Here is a summary of common questions and answers about PV power stations, hoping to help more people understand PV systems and use them correctly, allowing each power station to perform better and benefit both the installers and society.
1. Can we install wire mesh protective screens to prevent PV modules from being hit by heavy objects?
Answer: It is not recommended to install wire mesh protective screens. Adding wire mesh to the PV array may create shadows on the modules, leading to hot spot effects and affecting the power generation efficiency of the entire PV station. Moreover, qualified PV modules have passed the ice ball impact test, so there is generally no need to install protective screens.
2. What environmental requirements are there for the installation of rooftop PV systems?
Answer: If there are significant sources of dust pollution, strong winds, or heavy smoke around the PV power generation system, it will affect sunlight exposure, leading to a decrease in power generation.
3. For building-integrated distributed PV projects, how should we consider the color, transparency, size, and shape of PV modules?
Answer: For color, choose modules that match or are similar to the building color. For transparency, consider the building's lighting requirements to meet indoor lighting needs and avoid secondary lighting. Also, make full use of building space and area, reasonably select size and shape, and ensure proper balance and optimization with professional technical design.
4. Should the PV power generation system be disconnected during thunderstorms?
Answer: Distributed PV power generation systems are equipped with lightning protection devices, so there is no need to disconnect them. For added safety, you can choose to disconnect the circuit breaker switch of the combiner box to cut off the circuit connection with the PV modules, avoiding damage from direct lightning that the lightning protection module cannot eliminate. Maintenance personnel should promptly check the performance of the lightning protection module to avoid hazards caused by its failure.
5. What fire prevention and firefighting issues should be noted for household distributed PV power generation systems?
Answer: Do not store flammable and explosive materials near the distributed power generation system, as the loss of life and property in case of fire is immeasurable. In addition to basic fire safety measures, PV systems are required to have self-detection, arc, and fire recognition functions to reduce the likelihood of fire. Also, ensure that fire and maintenance channels are reserved every 40 meters and that there are easily operable emergency DC system cutoff switches.
6. How can building-integrated PV power generation systems prevent lightning?
Answer: Lightning hazards are primarily divided into direct lightning strikes and indirect lightning strikes. For direct lightning protection, establish metal lightning rods and grounding wires on tall buildings to discharge the electric charge from thunderclouds. For indirect lightning protection, add lightning arresters to the PV system, such as in the combiner box and inverter, to protect against indirect lightning strikes.
7. Will there be insufficient power in cold winters?
Answer: The power generation of PV systems is indeed affected by temperature, but the impact is minimal. The main factors affecting power generation are irradiance intensity and sunlight, as well as the operating temperature of the solar modules. In winter, due to lower temperatures and shorter daylight hours, power generation is generally less than in summer, which is normal.
8. Can the electricity generated by the distributed PV system during the day be stored for nighttime lighting?
Answer: Yes, the electricity generated by the distributed PV system during the day can be stored for nighttime lighting by adding controllers and batteries. The controller stores the electricity generated by the PV system in the battery during the day and releases it at night for lighting. Without energy storage equipment, if the grid is disconnected, the system will stop working. However, if the grid-tied inverter is replaced with an intelligent microgrid inverter (a hybrid inverter for grid-tied and off-grid), the system can continue to operate normally.
9. Will the PV power generation system still work on continuous rainy or smoggy days?
Answer: PV modules can generate electricity under certain low light conditions. While smog does affect PV power generation, it generally reduces efficiency by no more than 5% (except in severe smog conditions). On average, the power generation on rainy days is only 10%-20% of normal. Due to continuous rainy or smoggy weather, if the solar radiation intensity is too low to reach the inverter's startup voltage, the system will not work. Grid-tied systems operate in parallel with the power grid, so if the PV system cannot meet the load demand, the grid will automatically supply power, preventing power shortages or outages.
10. Are there any restrictions on the installation locations of PV modules?
Answer: The extreme operating temperature range for PV modules is -40°C to 85°C, and it is recommended to install them in environments with temperatures between -20°C and 50°C. This temperature range refers to the lowest and highest monthly average temperatures at the installation site. While there are no altitude restrictions for module installation, other electrical equipment in the system may have altitude limitations.
11. What electrical safety requirements should be observed during installation? Is there a risk of electric shock?
Answer: As long as there is sunlight, PV modules generate electricity, so it is impossible to completely cut off the power during the day. Additionally, due to the accumulation of series-connected voltages, the corresponding ground voltage can be very high. Therefore, strictly follow the installation and usage instructions provided by the system supplier, and have the installation performed by professional personnel. The wiring parts of the equipment should use professional connectors with IP65 protection levels. Electrical equipment also has air switches for protection, preventing electric shock hazards. Pay attention to protective measures during rainy and snowy weather. Specific requirements include:
- Use insulated tools when installing modules, and avoid wearing metal accessories.
- Do not disconnect electrical connections under load.
- Keep connectors dry and clean, and do not insert other metal objects into connectors or make electrical connections in other ways.
- Do not touch or operate PV modules with broken glass, detached frames, or damaged back panels unless the modules are electrically disconnected and you are wearing personal protective equipment.
- Do not touch wet modules unless cleaning them according to the cleaning manual. Always wear personal protective equipment or rubber gloves when handling wet connectors.
12. What are the characteristics of module failure?
Answer: Common aging phenomena in crystalline silicon modules include cell cracking, hot spots, EVA discoloration, backsheet cracking, and snail trails, which are visible to the naked eye. Issues like hot spots, solder joint failures in junction boxes, diode failures, and potential-induced degradation (PID) are not visible but can cause uneven heating of the cells and significant power generation drops. These can be detected through technical means. Regular inspections and tracking of power generation can help identify abnormal appearances or sudden power drops, indicating possible module failure. It is recommended that PV stations equip infrared thermal imagers to quickly detect and locate faulty modules. Contact the manufacturer for analysis and handling if module failure is detected; do not attempt to repair the failed modules yourself.
13. Which components need grounding during PV system installation?
Answer: It is recommended that all non-current-carrying metal parts and equipment casings in the PV power generation system be grounded, such as PV modules, module racks, and inverter casings. PV modules have pre-drilled grounding holes for direct series protection grounding. The grounding terminal of the inverter can be directly grounded or connected in parallel with the grounding line of the grid-tie cabinet.
14. How to select an inverter? How should PV inverters and modules be paired?
Answer: Generally, configure inverters according to system requirements and match the inverter's power rating with the maximum power of the PV array. The rated output power of the selected PV inverter should be close to the total input power to save costs. Typically, a 1:1 ratio is used for pairing, but most inverters can support overloading by up to 1.2 times or more.
15. What is MPPT?
Answer: MPPT stands for Maximum Power Point Tracking. It ensures that the inverter keeps the output power of the solar modules at the maximum value. The inverter initiates this function, and it targets the modules. MPPT efficiency is a key indicator of the inverter's ability to generate power efficiently.
16. What does IP65 mean?
Answer: IP65 indicates the protection level of the inverter. Generally, string inverters must reach IP65 protection to ensure outdoor installation and have dust and water resistance.
17. Can the inverter and modules leak electricity?
Answer: No, as long as the system is installed according to the PV system design, with firm wiring and good grounding, there will be no such issues.
18. Does surface damage to PV modules affect their performance?
Answer: Surface damage to the modules will lead to abnormal power generation and may cause electrical leakage.
19. Why is the inverter's power generation low?
Answer: Low inverter power generation can have various causes, which should be identified by checking each component. Ensure proper matching between the PV panels and the inverter, check the normal operation of both, and verify firm connections of all components.
20. Can the inverter be installed outdoors?
Answer: Yes, the product is designed to meet IP65 standards and can operate normally as long as it is not submerged. When installed outdoors, ensure that the device is not directly exposed to sunlight to avoid over-temperature derating.
21. Does the inverter consume power at night when it is not generating electricity?
Answer: Theoretically, it consumes a little power due to the filter circuit on the output side of the inverter, but this consumption is very low
, typically around 1W, which can be ignored.
22. What can the LCD display on the inverter show?
Answer: The LCD can display information on daily, monthly, and yearly power generation, as well as total power generation, current operating status, equipment parameters, and various historical information.
23. Does the inverter automatically start and stop?
Answer: The inverter automatically starts in the morning when the PV module power meets the inverter's startup power. It stops at night or when the module power drops to a low level.
24. Why does the power generation vary with different inverter installations?
Answer: The main reasons include orientation, shading, dust coverage, cable lengths, temperature, inverter efficiency, and environmental factors. High inverter efficiency and reliability also impact power generation. Besides ensuring proper orientation and angles, shading and cleanliness should also be maintained.
If you're interested in learning more about our solar energy storage offerings, we encourage you to explore our product line. We offer a range of panels and battery that are designed for various applications and budgets, so you're sure to find the right solution for your needs.
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Post time: Jul-07-2024
