PV Junction Box Manufacturing: Precision from Installation to Encapsulation

Within the intricate manufacturing chain of photovoltaic modules, the junction box serves as a core component for power transmission and safety protection. Its four critical manufacturing processes—installation, soldering, potting, and lid sealing—directly impact the module's power generation efficiency and service life. This article provides an in-depth analysis of the technical essentials and industry standards for each process, based on the latest industry standards and best practices.

Installation Process: Precise Positioning Establishes Safety Foundation

Junction box installation must strictly adhere to GB/T 37410-2019 standards, requiring a clearance tolerance of ≤0.5mm between the box body and the solar panel backsheet to ensure stable electrical connections. Key operational characteristics include:

1. Positioning Calibration: Utilize a laser positioning system to align the junction box center with the solar panel's main busbar, maintaining an error tolerance of ±0.3mm.

2. Fixing Method: Employ high-strength silicone adhesive bonding with a curing time of 48 hours, achieving a pull-off force ≥180N.

3. Cable Pre-processing: Per IEC 62852 standards, cables are pre-cut with a 1.5m allowance and protected by double-layer insulated sleeves.

(Industry data indicates that every 1mm increase in installation error raises module failure rates by 15%, underscoring the critical importance of precise positioning).

Welding Process: Thermal Control Technology Safeguards Diode Integrity

The core challenge in welding lies in balancing electrical conductivity with thermal damage risk. Current mainstream processes include:

1. Constant-temperature soldering iron: Temperature controlled between 255-275°C, soldering time ≤3 seconds. Requires use of Sn63Pb37 solder with silver content ≥3%.

2. Infrared Preheating + Soldering Iron: Reducing thermal shock through 100-150°C infrared preheating allows soldering iron temperature to be lowered by 20-40°C, decreasing cold solder joint rate from 8% to 0.5%.

The T/ZZB 0260-2017 standard explicitly requires: contact resistance at weld points ≤1.5 mΩ, and tensile testing must withstand ≥15 N stress. After implementing an AI vision inspection system, a leading enterprise reduced its weld defect rate from 2.3% to 0.1%.

Potting Process: Sealing Performance Determines Component Lifespan

The potting stage directly impacts the junction box's waterproof and dustproof capabilities, requiring compliance with IP65 protection rating standards:

1. Material Selection: Utilizes silicone potting compound with thermal conductivity ≥0.8 W/(m·K) and temperature resistance from -40°C to 150°C.

2. Vacuum Potting Technology: Eliminates air bubbles via a -0.09 MPa vacuum environment, achieving potting layer thickness uniformity with ≤0.2 mm deviation.

3. Curing Process: Cured at 70°C for 2 hours, achieving Shore A hardness of 60±5.

Comparative laboratory testing demonstrates that premium encapsulation extends junction box lifespan from 10 to 25 years and increases salt spray test pass rates from 78% to 99%.

Lid Manufacturing Process: Sealing Structure Forms Protective Barrier

The lid seal must pass the IP55 test specified in GB/T 4208-2017:

1. Seal Design: Utilizes silicone rubber O-rings with compression ratio controlled between 25%-30%.

2. Locking Mechanism: Features a four-point locking design with an opening/closing force requirement of 10-15N.

3. Air Tightness Testing: Employing the pressure decay method, the pressure drop at 10kPa for 30 seconds must be ≤0.5kPa.

Industry case studies demonstrate that the optimized box lid structure reduces power decay by 40% when components operate in an 85°C/85%RH humid-heat environment.

Future Outlook: Smart Manufacturing Drives Industry Upgrades

As photovoltaic module power output surpasses 700W, junction box current-carrying capacity must be enhanced to exceed 25A. Against this backdrop, industry-leading enterprises are spearheading three major transformations:

1. Fully Automated Production Line: A company's smart factory achieves full automation across welding, potting, and inspection processes, boosting single-line output by 300%.

2. Material Innovation: Developed nano-composite potting compound elevates thermal conductivity to 1.2W/(m·K), enhancing heat dissipation efficiency by 50%.

3. Smart Monitoring: Junction boxes integrated with temperature sensors provide real-time operational feedback, achieving 92% accuracy in fault prediction.

Driven by the dual carbon goals, the manufacturing of photovoltaic junction boxes is transitioning from traditional processes to precision manufacturing. Companies that master core process standards will gain a competitive edge in a market where global photovoltaic installations are growing at an average annual rate of 25%—and ChinTiyan is at the forefront of this transformation, committing to advancing precision manufacturing technologies and delivering high-reliability PV junction box solutions for the global renewable energy industry.