The anti-freezing maintenance of solar panels in cold environments needs to take into account both equipment performance and adaptability to extreme weather to avoid efficiency decline or mechanical damage caused by low temperatures. The following are the core points of anti-freezing maintenance in cold environments:
First, prediction of the impact of low temperatures on solar panels
Changes in material properties
Low temperatures can cause the encapsulation materials of solar panels (such as EVA film) to shrink, which may lead to delamination at the edges of the components or separation of the glass from the backsheet. Special attention should be paid to areas where the operating temperature is below -20℃ (such as Northeast China and Northern Europe).
The silicone sealing ring inside the junction box may harden, leading to sealing failure. It is necessary to check its elasticity in advance (it should return to its original shape within 10 seconds after being gently pressed by hand).
Attenuation of electrical performance
The open-circuit voltage (Voc) of the battery cells increases at low temperatures and may exceed the maximum input voltage of the inverter (for example, the Voc of a certain component at -25℃ is 15% higher than that at 25℃). It is necessary to confirm whether the withstand voltage value on the DC side of the inverter matches.
The outer sheath of the cable (such as PVC material) is prone to brittleness below -30℃. It is necessary to check whether there are cracks or loose joints in the cable.
Second, key measures for anti-freezing maintenance
The surface of the component is protected from snow and ice
Tilt Angle optimization: Ensure that the component installation Angle is ≥ local latitude +10°, and utilize gravity to accelerate the sliding of snow. For example, in the Beijing area (approximately 40° latitude), it is recommended that the installation Angle be ≥50°.
Mechanical snow removal restrictions: It is prohibited to strike components with metal tools to prevent hidden cracks in the glass. It is recommended to use a soft rubber scraper or high-pressure air for blowing (pressure ≤0.5MPa), and the operation should be carried out after sunrise when the components are heating up (to prevent the glass from cracking due to temperature difference stress).
Ice formation treatment: If icicles form at the edge of the component, they should be slowly melted with warm water (≤40℃) when the ice layer thickness is less than 2cm. Direct fire roasting or pouring with boiling water is strictly prohibited.
Anti-freezing of the electrical system
Cable insulation: For DC cables exposed outdoors (especially the section from string to combator box), install self-limiting temperature heating tapes to maintain the temperature above -5℃ and prevent the internal electrolyte from freezing.
Junction box protection: Wrap 10mm thick rubber and plastic insulation cotton outside the junction box and seal it with waterproof tape to prevent condensation water from seeping in and causing a short circuit.
Inverter preheating: Before starting at low temperature, ensure that the built-in heating module of the inverter is working properly (automatically starts when the ambient temperature is below 0℃), or turn on the auxiliary heating function 30 minutes in advance.
Structural and foundation anti-freezing
Anti-rust treatment for brackets: In cold regions, hot-dip galvanized steel (with a zinc coating thickness of ≥85μm) should be used, and anti-rust paint should be reapplied every two years (with a focus on bolt connections).
Foundation anti-frost heaving: For concrete foundations directly buried in the frozen soil layer, a 30cm thick coarse sand frost barrier layer should be set at the top of the foundation to prevent foundation cracking caused by frozen soil expansion.
Fastener inspection: Metal shrinkage at low temperatures may cause bolts to loosen. A torque wrench should be used to retighten them at 90% of the design value (for example, the torque of an M12 bolt should be 50N·m±5%).
Third, operation monitoring and fault response
Real-time data monitoring
Focus on monitoring the following parameters:
Component temperature (It is recommended to install a surface temperature sensor, and the alarm threshold is set at -40℃);
Dc side voltage (if it exceeds the rated value of the inverter by 110%, the unloading circuit needs to be started immediately);
Humidity in the combiner box (if the relative humidity is greater than 70%, the dehumidification module needs to be activated).
Use an infrared thermal imager to scan the components monthly to identify local low-temperature hotspots (which may be caused by snow cover or hidden cracks).
Rapid fault handling
Component hot spot: If it is found that the temperature of a single component is more than 10℃ lower than that of adjacent components, the component should be immediately covered and the machine stopped for inspection (it may be due to the failure of the bypass diode or the breakage of the battery cells).
Cable breakage: Cables become brittle and prone to breakage at low temperatures. Cold shrink terminal heads should be used for repair and wrapped with waterproof self-adhesive tape (temperature resistance range -55℃ to 105℃).
Inverter shutdown: If the IGBT module is over-temperature protected due to low temperature, it needs to be restarted after the ambient temperature rises above -10℃ or forced air cooling is enabled.
Fourth, long-term adaptive improvement
Equipment selection optimization
Select low-temperature type components (such as using high-impact-resistant glass and passing the mechanical load test at -40℃ in the IEC 61215:2021 standard).
The inverter needs to meet a wide operating temperature range of -30℃ to +60℃ and be equipped with an MPPT algorithm to optimize the low-temperature start-up performance.
System design improvement
Increase the component spacing (it is recommended to expand it by 20% compared to the conventional design) to reduce the secondary accumulation when snow slides off.
A wind and snow retaining wall (with a height of ≥2 meters and a ventilation rate of 30% to 40%) is set up on the north side of the power station to reduce the speed of snow accumulation.
Maintenance strategy adjustment
The frequency of winter maintenance has been increased to once a month (with a focus on checking the conditions of snow accumulation, ice floes and cables).
Establish an emergency supplies warehouse to store low-temperature grease (applicable to -50℃), anti-freezing glass cleaner (freezing point ≤-40℃), and spare parts for heating tapes.
Fifth, handling of special scenarios
Maintenance after the snowstorm
The snow should be cleared within 24 hours after the snow stops to prevent the snow from compacting and forming an ice shell.
Check whether the component is deformed due to snow compression (the maximum allowable deformation is ≤ 0.1% of the component length).
Coping with the temperature difference between day and night
In areas where the daily temperature difference exceeds 30℃, double-layer glass components (inner tempered glass + outer semi-tempered glass) should be used to reduce thermal stress.
Start the inverter to preheat one hour before sunrise every day to prevent the capacitor from bursting during cold start.
