Why Should Potting Glue be Used to Seal Solar Junction Boxes?

In the context of photovoltaic systems, the solar junction box is like a key hub connecting photovoltaic modules and inverters. Its reliability directly affects the power generation efficiency and the service life of equipment. The potting adhesive potting process is the core technology that safeguards the long-term stable operation of this hub, playing an irreplaceable role in the complex and ever-changing outdoor environment.

Its four core protective values, like four solid barriers, build an all-round defense for the junction box.

First, extreme environment isolation. The dense elastic colloid formed after the potting adhesive cures will completely wrap the internal circuit, thus achieving IP68-level waterproof and dustproof effects. Just look at the photovoltaic power stations in rainy areas: the water ingress failure rate of junction boxes treated with potting is only 0.3%, far lower than the 8.7% of non-potted products. Behind this slight difference is the effective avoidance of short-circuit risks.

Next, electrical insulation enhancement. High-quality potting adhesive can achieve a volume resistivity exceeding 10¹⁴Ω・cm and a breakdown voltage of no less than 20kV/mm. Such performance is sufficient to clamp the leakage current between terminals within 5μA, stably meeting the strict electrical safety requirements of the IEC 61215 standard, and is especially suitable for high-voltage component systems — isn’t this the most solid interpretation of the word "safety"?

The ability of thermal shock buffering is also not to be underestimated. When photovoltaic modules are working, the surface temperature of the junction box often fluctuates drastically between -40℃ and 85℃. However, the potting adhesive, with its low thermal conductivity of 0.2-0.3W/m・K and high elasticity brought by a Shore hardness of 60-80A, can just alleviate the difference in thermal expansion and contraction between metal terminals and plastic shells. Because of this, the junction box can still remain intact even after 2000 thermal cycle tests.

As for mechanical damage protection, the buffer layer formed by the cured colloid can not only resist vibration and impact during installation and transportation — fully complying with the ISTA 3A transportation standard — but also prevent line exposure caused by pecking from insects and birds. Data from a desert power station is sufficient to confirm: the mechanical damage rate of potted products has been reduced by 92%.

Protection Dimension	Defect Rate of Non-potted Products	Improvement Effect After Potting	Core Index Requirements
Waterproof and Moisture-proof	8.7%	Reduced to 0.3%	IP68 protection level
Electrical Safety	5.2%	Reduced to 0.1%	Volume resistivity ≥ 10¹⁴Ω・cm
High and Low Temperature Resistance	12.5%	Reduced to 1.8%	No cracking in cycles from -40℃ to 85℃
Resistance to Mechanical Impact	7.3%	Reduced to 0.6%	No damage under 1000g acceleration impact

Nowadays, as photovoltaic power stations continue to extend to extreme areas such as high altitudes, coastal regions, and deserts, the performance requirements for potting adhesives are constantly rising. The current mainstream silicone rubber potting adhesives can withstand a temperature range of -60℃ to 150℃ and have passed the UL94 V-0 flame retardant certification, providing protection for solar junction boxes throughout their entire life cycle. This process has never been just a rigid requirement of industry standards, but also a solid confidence for photovoltaic systems to fulfill their 25-year service life commitment.