DC Cable

What is DC cable

DC cable, also called PV cable or solar cable, is the specialised electrical cable designed to carry direct current from solar PV modules to combiner boxes and on to the inverter. It must withstand the unique conditions of solar installations: high DC voltage (up to 1500 V), constant UV exposure, weather extremes, 25-year service life and field-installable termination.

Indian PV cable specifications follow IS 17048 and the equivalent international standards IEC 62930, TUV 2 PfG 1169 and EN 50618. Typical construction is a single-core stranded copper conductor with double insulation: an inner cross-linked polyolefin (XLPO) layer for electrical insulation and an outer XLPO or thermoplastic elastomer (TPE) sheath for UV and mechanical protection.

Cross-section selection balances cost against voltage drop and ampacity. Most Indian rooftop systems use 4 mm² PV cable for string runs. Larger 6 mm² and 10 mm² appear in C&I and combiner box DC trunks. Utility plants use 16 mm² to 70 mm² in DC trunk runs.

Why DC cable matters

Yield. Voltage drop in DC cable directly reduces inverter input, reducing yield.

Safety. Inadequate insulation causes arc faults, fires and inverter Riso trips — the same grounding and insulation issues covered in our solar inverter grounding safety guide.

Longevity. PV-rated cable is designed for 25-year exposure; substitution fails in 2 to 5 years.

Regulatory compliance. IS 17048 and CEA Measures Relating to Safety require PV-grade cable.

System reliability. Most DC field failures trace back to cable termination or selection.

DC cable specifications

Technical deep dive

Ampacity (free air, 30°C)

Derate for grouping, conduit installation and temperature.

Voltage drop calculation

Where R is per-metre resistance (Ω/m) and L is one-way length (m).

Resistance vs cross-section

Target voltage drop

Real-world applications

Rooftop residential solar.

C&I rooftop solar.

Combiner box to inverter trunk runs.

Ground-mount string runs, sized alongside the array layout in ground mount solar projects.

Charge controller PV inputs.

EV solar canopy DC connections.

Common DC cable problems

UV degradation in non-PV-rated cable.

Insulation damage from rodents.

Loose connections at MC4 causing localised heating.

Inadequate cross-section causing voltage drop and yield loss.

Cable damage during installation (cuts, abrasion).

Water ingress at connector boundaries.

Best practices

Use only IS 17048 or IEC 62930 certified PV cable.

Size for voltage drop target, not just ampacity.

Use conduit in rodent-prone areas.

Avoid sharp bends (minimum bend radius typically 5x diameter).

Use proper cable glands and seals at enclosure entries.

Crimp MC4 with manufacturer’s tool.

Document cable cross-sections on the single line diagram.

Inspect annually for UV cracking and rodent damage.

Comparison: PV cable vs alternative

Indian market context

Major Indian PV cable brands: Polycab, Havells, KEI, RR Kabel, Finolex, Universal Cables, Apar — sourcing decisions covered in our inverter procurement guide for EPCs.

ALMM does not separately list cables. IS 17048 compliance is the quality benchmark.

CEIG drawing approval, prepared as part of the electrical drawing package, verifies cable cross-sections.

Standards and certifications

Common mistakes

Using house wire instead of PV cable.

Skipping voltage drop calculation.

Cable run through sun without conduit.

Mixing brands or PV ratings within one string.

Bending tighter than minimum radius.

Inadequate cable gland sealing.

Key takeaways

DC cable is specialised PV-rated cable carrying solar DC from modules to inverter. IS 17048 and IEC 62930 set the standards: 1000 to 1500 V DC rating, double XLPO insulation, UV-resistant outer sheath, 25-year design life. Sizing for voltage drop target (1 to 2 percent) and current ampacity, with proper termination and routing, ensures safe and efficient DC connection across the 25-year project life.

Further reading

For how DC Cable plays out in real projects, these guides go deeper:

• Inverter Battery Connection Diagram and Sizing Guide for Hybrid Solar
• String Voltage vs MPPT Voltage: Inverter Guide
• Solar Inverter Ground Fault Error, Troubleshooting
• How Does a Solar Power System Work in India?

Sources

• IS 17048, Indian Standard for solar photovoltaic cables.
• IEC 62930, Electric cables for photovoltaic systems.
• TUV 2 PfG 1169, Solar cable certification.
• EN 50618, European solar cable standard.
• UL 4703, US PV wire.
• CEA Measures Relating to Safety and Electric Supply Regulations 2023.
• Manufacturer documentation from Polycab, Havells, KEI, RR Kabel.
• CEA (Technical Standards for Connectivity of the Distributed Generation Resources) Regulations, 2013 (as amended 2019), Central Electricity Authority.
• IS 732, Indian wiring code.