A solar cable, sometimes referred to as a PV cable, is a specialized electrical conductor designed to transmit direct current (DC) electricity generated by solar panels to inverters, charge controllers, and storage batteries. Unlike standard building wires, solar cables must endure long-term exposure to sunlight, fluctuating temperatures, humidity, and mechanical stress.
The expected service life of a PV system is 25–30 years, and the cables must match this longevity while maintaining consistent electrical performance. This requirement makes their design and materials far more demanding compared to indoor building wires.
UV and Weather Resistance
PV cables are exposed directly to sunlight and outdoor conditions for decades. Their insulation is typically cross-linked polyethylene (XLPE or XLPO), which resists UV degradation, ozone, and thermal aging.
Wide Operating Temperature Range
Solar cables usually operate from -40℃ to +90℃, with some high-grade types tolerating up to 120℃. This allows them to withstand daytime heating and nighttime cooling cycles without cracking.
Moisture, Oil, and Chemical Resistance
In humid or industrial environments, solar cables must resist corrosion and chemical attack. LSZH (Low Smoke Zero Halogen) sheaths are often used to minimize toxic emissions in case of fire.
Flame Retardancy
Safety standards require PV cables to self-extinguish when ignited, reducing fire propagation risks in rooftops or ground-mounted arrays.
DC System Compatibility
Solar cables are rated up to 1500V DC, matching modern PV array voltages. They are optimized for low resistance to minimize energy loss in long cable runs.
Voltage Rating:
600V DC for small-scale residential systems
1000V–1500V DC for commercial and utility-scale projects
Current Capacity (Ampacity):
The cable’s cross-sectional area determines current capacity. For instance:
4 mm² copper cable: ~25–30A DC
6 mm² copper cable: ~35–45A DC
10 mm² copper cable: ~55–70A DC
Proper sizing must follow NEC (National Electrical Code) or IEC standards, usually applying a 125% safety margin over the array’s short-circuit current.
Conductor:
Tinned copper is the standard due to excellent conductivity and corrosion resistance.
Stranded conductors improve flexibility, critical for rooftop installations.
Aluminum is cheaper but less common, requiring anti-corrosion connectors.
Insulation:
XLPO / XLPE: Cross-linked polymers with high thermal and UV stability.
EVA (Ethylene Vinyl Acetate) may be used in low-cost models but has shorter durability.
Sheath:
XLPO sheath or LSZH compounds for mechanical protection, fire safety, and environmental resistance.
| Feature | Solar Cable (PV Cable) | Standard Building Wire (e.g., THHN) |
|---|---|---|
| Application | Outdoor PV arrays, exposed conditions | Indoor, conduit-protected |
| Voltage Type | DC (600–1500V) | AC (120–600V) |
| UV Resistance | Excellent | Poor (quick degradation outdoors) |
| Service Life | 25–30 years | 20–30 years indoors only |
| Flexibility | Stranded, easy to route | Often rigid |
The clear distinction highlights why PV-specific cables are mandatory for solar installations.
String Cables: Connecting solar panels in series.
Array Cables: Collecting multiple strings and feeding into the DC bus.
Inverter Cables: Linking arrays to inverters.
Battery Cables: Connecting inverters/charge controllers to energy storage units.
Each connection point requires cables sized for its specific voltage, current, and environmental exposure.
UV Degradation: Using non-rated wires outdoors leads to brittle insulation.
Overheating: Undersized cables generate excessive heat under high current.
Mechanical Stress: Rodent damage, abrasion, or improper bending radius.
Moisture Ingress: Damaged sheaths allow water to corrode conductors.
Faulty Terminations: Loose connectors increase resistance and heat buildup.
Most failures can be prevented through correct cable selection, proper routing, and quality connectors.
UV Resistance Test: Long-term exposure to simulated sunlight.
Thermal Cycling: Alternating hot and cold to check insulation endurance.
Insulation Resistance: Verifying high resistance against leakage currents.
Ampacity Test: Confirming cable can carry rated current safely.
Flame Test: Assessing fire safety compliance.
Manufacturers who comply with IEC 62930, EN 50618, or UL 4703 standards ensure cables meet international safety and durability benchmarks.
System Voltage: Ensure cable rating matches PV system (e.g., 1000V DC).
Current Load: Size cables with 125% of Isc (short-circuit current).
Environment: For coastal sites, choose tinned copper; for fire-risk areas, opt for LSZH.
Certification: Look for UL/IEC-approved cables for compliance and safety.
Solar cables are not just “wires”—they are the lifelines of a photovoltaic system. Their specialized materials, construction, and performance standards ensure safe, efficient, and long-lasting operation under harsh environmental conditions. Choosing the right solar cable is crucial for system reliability, safety, and cost efficiency over decades of service.
By understanding the engineering behind PV cables, installers, designers, and end-users can maximize solar power output while avoiding costly failures.
