Choosing the right DC cable is a crucial step in designing a reliable and efficient solar rooftop system. While both 4mm² and 6mm² solar cables meet Australian standards for photovoltaic installations, their performance differs significantly depending on application size, distance, and current load.
This guide compares the two options and helps you decide which cable size is best suited for your project — whether it’s a compact residential setup or a larger commercial rooftop installation.
Why Cable Sizing Matters in Solar Installations
DC cables play a vital role in transferring power from solar panels to inverters. Choosing the wrong cable size can lead to excessive energy loss, overheating, or even safety risks.
Smaller systems may tolerate lower current ratings, but as installations scale up, so does the demand for proper cable dimensioning and cable management.
Using undersized cables in large systems results in voltage drops and reduced efficiency over time.
Performance and Safety Implications
The cross-sectional area of a cable affects its resistance and heat dissipation. A larger conductor (e.g., 6mm²) offers better current flow, minimizing losses and improving safety.
- Resistance to heat: Thicker cables reduce risk of overheating
- Reduced voltage drop: Ensures power reaches the inverter efficiently
Technical Comparison: 4mm² vs 6mm² Solar DC Cables
Both cable types supplied by Solar Rains are TÜV-certified and meet IEC 62930 and EN 50618 standards. Below is a detailed breakdown based on the official datasheets:
| Specification | 4mm² DC Cable | 6mm² DC Cable | Verdict |
| Conductor Size | 2x4mm² (56 strands) | 2x6mm² (84 strands) | 6mm handles more current |
| Max Current @60°C | 55A | 70A | 6mm wins for large loads |
| Resistance (Ω/km) | ≤5.09 | ≤5.09 | No major difference |
| Cable Dimensions (mm) | 5.5 x 11.2 | 6.0 x 12.3 | 4mm is more compact |
| Insulation & Jacket | XLPO (Electron Beam) | XLPO (Electron Beam) | Same durability |
| Temperature Range | -40°C to 120°C | -40°C to 120°C | Both suitable for Australian conditions |
| UV & Flame Resistance | Passed 720h UV, EN 60332-1-2 flame test | Passed 720h UV, EN 60332-1-2 flame test | Equal outdoor performance |
Strengths of 4mm² DC Cable
- Lightweight and flexible
- Suitable for small systems under 3kW
- Easier to route in narrow rooftop spaces
Strengths of 6mm² DC Cable
- Higher current capacity
- Ideal for larger systems and long cable runs
- More future-proof for potential expansion
Which One Should You Choose?
For Small Residential Installations
Choose 4mm² solar cable if your inverter is close to the panels, the total system size is below 3kW, and compact routing is essential.
For Medium to Large Installations
Opt for 6mm² DC cable when dealing with 5kW–10kW systems, longer distances between panels and inverter, or higher expected current flow.
Always consult a licensed solar installer to verify cable sizing per AS/NZS 3000 and voltage drop regulations.
Optimizing Cable Management on Rooftops
Regardless of cable size, proper cable management is essential for a safe and long-lasting solar installation.
Best Practices Include
- Using cable trays to shield cables from mechanical damage
- Securing routes with nylon cable ties or steel clips
- Protecting terminations with cable glands to prevent moisture intrusion
Efficient cable layout helps avoid overheating, simplifies maintenance, and ensures long-term performance.
Summary: 4mm vs 6mm – Choosing the Right DC Cable
| Choose 4mm² if | Choose 6mm² if |
| Your system is under 3kW | You operate a 5kW+ system |
| Panel and inverter are close | You want higher current handling |
| You prefer easier installation | Your installation is spaced out or future-proofed |
Both cables provided by Solar Rains meet strict compliance requirements and ensure reliable, high-efficiency operation.
🔗 Explore Solar DC Cable 1500V (4mm & 6mm) – Solar Rains
Choosing between 4mm² and 6mm² DC cables depends on your rooftop configuration, current load, and safety expectations. Solar Rains offers TÜV-certified cables that meet Australian standards — giving you peace of mind, performance, and durability.
Get in touch with our team today to select the perfect cable for your solar project.
Frequently Asked Questions (FAQs)
No. 4mm² is not suitable for high current. Use 6mm² to avoid performance loss.
6mm is more expensive but delivers better current capacity and long-term savings.
Yes. Both models passed TÜV UV (720h) and EN60332-1-2 flame tests.
