In photovoltaic systems, cables are the "blood vessels" connecting modules, combiner boxes, and inverters. However, these "blood vessels" are constantly exposed to extreme environments: summer rooftop temperatures exceeding 70°C, winter outdoor temperatures dropping to -40°C, direct ultraviolet radiation, acid and alkali corrosion, and rodent and ant damage. Under such conditions, ordinary cables experience rapid aging and cracking of the insulation layer and powdering and peeling of the sheath, leading to anything from minor grounding faults to serious fires. Photovoltaic DC cables were developed precisely for this purpose. Based on the PV1-F standard, it features a layered design from conductor to sheath: high-purity oxygen-free copper stranded conductor (multi-strand fine filaments, tightly arranged) ensures low resistance, high conductivity, flexibility, and bend resistance; cross-linked polyolefin insulation layer (thickness 0.9mm±0.05, rated withstand voltage 1.5kVDC) withstands extreme temperature differences from -40℃ to +120℃, is dense and bubble-free, and prevents leakage and corona discharge; double-layer shielding layer (copper tape wrapping/mesh braiding, coverage ≥95%) balances the electric field, suppresses electromagnetic interference, and reduces partial discharge; special weather-resistant polyolefin sheath (thickness 1.8mm, A++ grade UV resistance, wear resistance >100,000 times) is flame-retardant, self-extinguishing (self-extinguishing <10s), waterproof, mildew-proof, oil-resistant, and acid and alkali-resistant.
This article dissects the technical secrets of photovoltaic cables, from structure to testing: conductor stranding gap, insulation thickness control, shielding overlap process, sheath weather resistance mechanism, and flame retardant combustion test comparison—allowing you to see the longevity genes of a "good cable".
From conductor to sheath, every parameter of the photovoltaic DC cable corresponds to the rigorous testing of real-world scenarios. The conductor uses tightly stranded 56/0.12mm high-purity oxygen-free copper wire, combining low resistance (sufficient current carrying capacity) with flexibility (easy to bend and lay on site); the insulation layer is uniformly coated with cross-linked polyolefin, with a thickness of 0.9mm, withstand voltage of 1.5kV, and temperature resistance of -40~+120℃, ensuring no aging or breakdown during long-term operation; the shielding layer is double-wrapped/braided, with a coverage rate of ≥95% and a conduction resistance of ≤1.5Ω/km, effectively suppressing partial discharge and electromagnetic interference; the sheath is thickened to 1.8mm with special polyolefin, with A++ level UV resistance (UL746C certification), abrasion resistance exceeding 100,000 cycles, and resistance to oil, acids, and alkalis; the flame retardant performance passes the IEC60332-1 test—after being burned with an open flame for 60 seconds, it self-extinguishes in less than 10 seconds after the flame is removed, with no dripping spread, a stark contrast to the "flame spread" of ordinary cables. These technical details boil down to one commitment: throughout the 25-year lifespan of a photovoltaic power station, the cable insulation will not age, the sheath will not powder, and the flame retardant will not fail. Construction and maintenance personnel must pay attention to the following: avoid scratching the conductor and insulation layer during wire stripping; ensure the bending radius is ≥6 times the outer diameter; ensure proper waterproof sealing at joints; and install conduit protection for buried sections. Choose PV1-F cables with TÜV and CCC certifications, and reject the short-sighted practice of "using general-purpose cables instead of photovoltaic-specific cables." Cables may be small, but safety is paramount—every meter of qualified cable is the cornerstone of a power station's stable operation for 25 years.
Special attention should be paid to ensuring that all terminals are securely tightened. Many power plants have had their terminals burned out because the wire ends were not properly tightened during installation.
The screws securing the solar panels and brackets must also be tightened securely; otherwise, strong winds can cause loose screws to fall off, eventually overturning and damaging the solar panels.
When installing the array, special attention must be paid to the polarity of the solar panels and the array itself. In one domestic photovoltaic power plant, the entire array burned out and failed due to reversed polarity and an accidental short-circuiting of the anti-reverse diode during construction. When the array was replaced, the polarity was not correctly connected, causing the array to fail again.
- Cables should not be operated under overload conditions, and the cable sheath should not show signs of expansion or cracking;
- Cable entry and exit points should be properly sealed, and there should be no holes larger than 10mm in diameter. If holes are present, they should be sealed with fire-resistant sealant;
- At locations where the cable exerts excessive pressure or tension on the equipment casing, the cable support points should be intact;
- Cable protective steel conduits should be free of perforations, cracks, and significant unevenness, and the inner wall should be smooth; metal cable conduits should not be severely corroded; there should be no burrs, hard objects, or debris. If burrs are present, they should be filed smooth and then wrapped tightly with the cable sheath;
- Accumulated materials and debris in outdoor cable wells should be cleaned promptly; if the cable sheath is damaged, it should be repaired;
- When inspecting indoor cable trenches, care should be taken to prevent damage to the cables; ensure proper grounding of the supports and good heat dissipation within the trench;
- The marker posts along the direct-buried cable route should be intact; there should be no excavation near the route; ensure that there are no heavy objects, building materials, or temporary facilities piled up on the ground along the route, and no corrosive substances discharged; ensure that the cable protection facilities on the exposed surface are intact;
- Ensure that the covers of the cable trench or cable well are intact; the trench should be free of water or debris; ensure that the supports in the trench are firm, and that the cable sheath and armor are not severely corroded;
- For multiple cables laid in parallel, the current distribution and power consumption should be checked to prevent cable burnout due to poor contact;
- Ensure that the cable termination is well grounded, the insulating sleeve is intact, and there are no traces of network discharge; ensure that the cable phase colors are clearly visible;
