A photovoltaic (PV) junction box is a connecting device between a solar cell array and the charging control unit. It is an essential component of a solar photovoltaic power generation system, accounting for less than 1% of the total weight but providing circuit protection. Its main function is to conduct the current generated by the modules and prevent hot spot effects, integrating electrical design, mechanical design, and materials science.
The device consists of a box body, a cover, diodes, cables, and MC3/MC4 connectors. The box body is made of UV-resistant PPO, and the cover is fitted with a breathable but waterproof membrane. Based on the sealing method, it can be divided into ordinary junction boxes (silicone sealing rings) and potted junction boxes (two-component silicone potting). Technical parameters include a maximum operating current of 20A/25A/30A, withstand voltage of 1000V, applicable temperature of -40～85℃, waterproof rating of IP68, and flame retardant rating of V-0. Selection requires matching the module power, short-circuit current, and diode parameters. Some products have built-in smart chips for module-level operation monitoring.
| Product Name | ML06A（25A） |
| Rated Voltage | 1500V |
| Insulation Material | PPO |
| Conductor Material | Tin-plated Copper |
| Ambient Temperature | -40℃～+85℃ |
| Product Temperature | -40℃～+125℃ |
| Security Class | DCII |
| Waterproof Grade | IP68 |
| Contact Resistance | ≤0.5mΩ |
| Connection System | 4mm², 6mm² |
| Wire Length | Standard 30cm (Custom lengths available) |
| Waterproofing Method | Potting Compound |
| Potting Amount | 8g×3 |
| Rated Current | 20A |
| Flame Retardant Rating | UL94-VO |
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