How to Maintain a PV Plant? State Grid Answers 8 Common O&M Questions（2）

1. On a scorching sunny day, do damaged vulnerable components need to be replaced immediately?

Immediate replacement is not recommended. If replacement is necessary, it is advisable to do so in the early morning or late afternoon. You should contact the power station’s operation and maintenance (O&M) personnel promptly, and have professional staff go to the site for replacement.

2. To prevent photovoltaic (PV) modules from being hit by heavy objects, can wire mesh protective screens be installed around PV arrays?

Installing wire mesh protective screens is not recommended. This is because installing such screens along PV arrays may cast local shadows on the modules, causing the hot spot effect—which negatively impacts the power generation efficiency of the entire PV power station. Additionally, qualified PV modules have all passed ice ball impact tests, so normal impacts will not affect the modules’ performance.

3. Will shading from building shadows, tree leaves, or even bird droppings on PV modules affect the power generation system?

Yes, such shading will have a significant impact on the power generation system. The electrical characteristics of the solar cells in each module are basically consistent; if not, the hot spot effect will occur on cells with poor electrical performance or those that are shaded. In a series connection, the shaded solar cell modules will act as loads, consuming the energy generated by other illuminated solar cell modules. At this point, the shaded modules will generate heat—that is the hot spot effect. In severe cases, this phenomenon can damage the solar modules. To avoid hot spots in series branches, bypass diodes must be installed on PV modules; to prevent hot spots in series circuits, DC fuses should be installed on each PV string. Even without the hot spot effect, shading on solar cells will still reduce power generation.

4. How to identify if a PV module in a PV array is faulty?

If you notice that the system’s power generation has decreased at the same time of day, or is lower compared to nearby systems with the same installation setup, the system may be abnormal. You can detect abnormal fluctuations in the monitoring data from the combiner box to identify if a module in the PV array is faulty. Then, contact professionals to diagnose the system using specialized equipment such as clamp meters and thermal imagers, and finally locate the faulty module.

5. How to properly utilize shutdown periods for maintenance?

Priority should be given to performing maintenance in the early morning or evening, when light intensity is low and the system is not operating. Before maintenance, take protective measures: wear insulating gloves and use insulated tools.

6. Is it sufficient to rinse PV modules with clean water and wipe them simply? Is there a risk of electric shock when wiping with water?

To avoid electric shock to humans and potential damage to modules caused by wiping them under high temperatures and strong sunlight, it is recommended to clean the modules in the early morning or late afternoon. For cleaning the glass surface of PV modules, use a soft brush and clean, mild water. Apply gentle force during cleaning to avoid damaging the glass surface. For modules with coated glass, take care to avoid damaging the coating layer.

7. How to handle long-term post-commissioning maintenance of the system? How often should maintenance be performed, and what does it involve?

Perform maintenance on components requiring regular inspection in accordance with the user manual provided by the product supplier. The main maintenance task for the system is wiping the modules: in areas with abundant rainfall, manual wiping is generally unnecessary; in non-rainy seasons, clean the modules approximately once a month; in areas with heavy dust, increase the frequency of cleaning. In areas with heavy snowfall, remove thick snow from the modules to avoid affecting power generation and uneven melting after snowmelt. Promptly clear trees or debris that shade the modules.

8. How to reduce the maintenance cost of a PV power generation system?

It is recommended to select system components and materials with a good market reputation and reliable after-sales service. Qualified products can reduce the incidence of faults. Additionally, you should strictly follow the system product manual and conduct regular inspections, cleaning, and maintenance of the system.