Although the power generation efficiency of solar panels drops significantly on rainy days, the stable operation of the system can still be guaranteed and long-term performance degradation can be reduced through scientific maintenance. The following are targeted measures proposed from four dimensions: power generation efficiency optimization, equipment protection, data monitoring and long-term maintenance strategies:
First, strategies for optimizing power generation efficiency
Component selection and improvement of weak light response
Priority should be given to component technologies with excellent weak light performance, such as HJT (heterojunction) or TOPCon (Tunnel Oxidized Passivated contact) cells. Their weak light response coefficient can reach over 95%, and they can still maintain high power generation efficiency when the light intensity is as low as 200W/㎡. For instance, the power generation of HJT modules on rainy and cloudy days is 10% to 15% higher than that of conventional PERC modules.
Double-sided power generation modules are adopted to increase power generation by utilizing the reflected light from the ground (such as white gravel or light-colored ground). On rainy and cloudy days, the power generation of bifacial modules can increase by 5% to 8%.
System matching and MPPT optimization
The inverter needs to have a multi-channel MPPT (Maximum Power Point Tracking) function to deal with power fluctuations caused by local occlusion or uneven lighting. For example, when some components are blocked by clouds, MPPT can quickly adjust to the maximum power point of other unobstructed components to reduce power generation losses.
Adjust the starting voltage and power threshold of the inverter to ensure it can still operate normally under low light conditions. Some inverters support reducing the starting voltage to below 100V, adapting to the weak light environment on rainy days.
Second, equipment protection and moisture-proof measures
Moisture-proof and insulating treatment
On rainy and cloudy days, the air humidity is high, which can easily cause condensation inside equipment such as component junction boxes and inverters, leading to short circuits or insulation failure. Moisture-proof silica gel or desiccant should be installed inside the equipment and replaced regularly.
Check all electrical connection parts to ensure good sealing and prevent water vapor from entering. For outdoor equipment, it is recommended to use junction boxes and connectors with a protection level of IP67 or above.
Drainage and water accumulation prevention
Clean the drainage channels and deflector pipes beneath the components to ensure that rainwater can be discharged smoothly and prevent water accumulation from soaking the foundation or corroding the supports.
Check whether the installation Angle of the components meets the design requirements (usually ±10° of the local latitude) to ensure that rainwater does not accumulate on the surface of the components.
Third, data monitoring and performance analysis
Real-time data collection and analysis
Deploy an intelligent monitoring system to collect parameters such as component temperature, irradiance, power generation capacity, and inverter efficiency in real time. Pay close attention to the PR (Performance Ratio) value on rainy and cloudy days. If the PR value is lower than 60%, system faults need to be investigated.
Correlation analysis is conducted using meteorological station data (such as rainfall and cloud coverage) with power generation to establish a power generation prediction model for cloudy and rainy days and optimize system scheduling.
Fault early warning and rapid response
Establish a three-level early warning mechanism:
Level 1 Warning (yellow) : Irradiance is below 150W/㎡ and persists for 1 hour, triggering the system’s self-check.
Level 2 Warning (Orange) : When the component temperature drops below 5℃ or rises above 40℃, activate the heating or cooling device.
Level 3 Warning (Red) : Power generation is 30% lower than the historical average for the same period. On-site maintenance should be arranged immediately.
Maintenance personnel are required to respond within 2 hours after receiving the warning and complete the troubleshooting within 48 hours.
Fourth, long-term maintenance and performance recovery
Regular cleaning and performance calibration
After rainy days, clean the surface of the components in time to remove mineral deposits (such as calcifications) in the rainwater and prevent the formation of stubborn stains. It is recommended to use a soft scraper and deionized water to avoid scratching the glass.
An IV curve test is conducted once every quarter to calibrate the deviation between the nominal power and the actual output power of the components. If the deviation exceeds 5%, it is necessary to further investigate component attenuation or connection faults.
System expansion and upgrade
For areas that are constantly affected by rainy days, it is advisable to consider expanding the system capacity. For instance, the original 10kW system is expanded to 12kW to make up for the power generation loss during rainy days.
Upgrade the inverter to a model that supports energy storage systems and pair it with lithium battery energy storage to achieve self-sufficiency in electricity during rainy and cloudy days.
Fifth, response to special scenarios
Energy storage management during continuous rainy days
The energy storage system needs to adjust its charging and discharging strategies according to the duration of rainy days. For instance, during three consecutive days of rainy and cloudy weather, maintain the state of charge (SOC) of the energy storage at 50% to 70% to prevent excessive charging and discharging from shortening the battery life.
Activate backup power sources (such as diesel generators) as emergency support to ensure power supply for critical loads.
Anti-mold treatment in high-humidity areas
Spray anti-mold coatings inside the junction box and inverter to prevent mold growth and circuit short circuits.
Regularly use a dehumidifier to dehumidify the equipment room and keep the relative humidity below 60%.
Sixth, maintenance effect evaluation
Verification of power generation increase
The effectiveness of the maintenance measures was evaluated by comparing the power generation data on rainy days before and after the maintenance. For instance, after the upgrade of low-light components was implemented, the power generation on rainy days increased by 12%.
Calculate the annual equivalent utilization hours (EUH) of the system. If the EUH is more than 15% lower than the local average level, the system configuration needs to be further optimized.
The service life of the equipment is prolonged.
Calculate the failure rates of key equipment such as components and inverters. If the failure rate drops by more than 30% after maintenance, it indicates that the maintenance strategy is effective.
The hot spot condition of the component is detected by infrared thermal imaging. If the area of the hot spot decreases by more than 50%, it indicates that the moisture-proof and cleaning measures are in place.
