How to Choose Between 4mm² and 6mm² Solar Cable

Selecting the right cable size is one of the simplest but most important decisions in any solar project. The choice between 4mm² Solar Cable and 6mm² solar cable determines how efficiently power moves from panels to inverters, how much heat builds up, and how long your installation will last under outdoor conditions.

For users sourcing cable directly from a Manufacturer with strong Production capacity, understanding these differences ensures you get the most stable and cost-efficient solution—especially for bulk orders or standardized project designs.

This guide breaks down key technical factors and gives you a clear, practical method to choose the correct cable size.

What Is 4mm² Solar Cable and When Is It Typically Used?

A 4mm² Solar Cable is one of the most common conductor sizes in small and medium photovoltaic systems. Its compact size, flexibility, and cost-effectiveness make it suitable for:

·Residential rooftop systems (1–6 kW)

·Short cable runs between panels and the combiner box

·Parallel panel strings with lower current

·Installations where voltage drop is within acceptable limits

·Users who prioritize easier routing and cleaner cable management

Because 4mm² cable is thinner, it has lower material cost and is easier to install through tight spaces. It is widely used by installers who want an efficient and standardized solution for smaller solar arrays.

What About 6mm² Solar Cable?

A 6mm² solar cable has a larger conductor cross-section, which enables it to carry more current and reduce voltage drop over longer distances. It is typically selected for:

·Commercial systems (10–50 kW)

·Longer cable runs from arrays to inverters

·Higher-current panel strings, especially in warm climates

·Systems where maximum efficiency is required

·Situations with strict safety margins or higher ambient temperatures

Though slightly more expensive, 6mm² cable improves energy yield in systems that operate near maximum capacity for long hours. When sourced from a high-quality Manufacturer, its durability and heat-resistance further enhance the long-term stability of solar installations.

Voltage Drop Comparison: The Key to Choosing the Right Size

Voltage drop is often the deciding factor in choosing between 4mm² Solar Cable and 6mm² cable. Too much voltage drop reduces system output and forces the inverter to work harder, leading to lower efficiency.

General rules:

·Short runs (<10 m): 4mm² is usually sufficient.

·Medium runs (10–20 m): Depends on current—both may work; choose based on efficiency goals.

·Long runs (20–40 m): 6mm² significantly reduces energy loss.

·High current strings (>10 A): 6mm² is recommended.

Installers often aim for <3% voltage drop, and the 6mm² cable performs better in maintaining that threshold.

Current-Carrying Capacity: How Much Power Can Each Cable Handle?

Cable ampacity varies by insulation quality, temperature rating, and installation environment. High-quality cables from a professional Photovoltaic Cable Manufacturer follow international standards such as:

·IEC 62930

·EN 50618

·TÜV-certified PV cable requirements

Typical ampacity comparison:

·4mm² Solar Cable: ~35–41 A

·6mm² Solar Cable: ~46–55 A

Higher ampacity ensures safer operation when sunlight intensity increases panel current during peak production hours.

Safety and Durability Considerations

When choosing between 4mm² and 6mm² cable, safety is as important as performance. Thickness directly affects:

·Heat tolerance

·Cable aging speed

·Overcurrent resistance

·Performance in extreme climates

Thicker cables offer greater safety margins. If your installation involves:

·Desert climates

·High rooftop temperatures

·Heavy UV exposure

·Long-distance DC runs

…then 6mm² cable is generally the more reliable choice.

Cost Difference: When Does 6mm² Become Worth It?

While 6mm² cable costs more due to higher copper content, the long-term gains often justify the investment.

6mm² is worth the extra cost if:

·You want maximum efficiency and lower losses

·Cable runs are long

·Ambient temperatures are high

·The system operates commercially or continuously

·Maintenance access is limited

·You need higher safety margins for long-term reliability

For small rooftop systems or plug-and-play residential kits, however, 4mm² Solar Cable remains the most cost-optimized solution.

A Simple Method to Choose the Right Cable Size

Use this decision guide:

1.System size < 6 kW?
Choose 4mm² unless cables exceed 20 meters.

2.System size 6–20 kW?
Choose 6mm² for main DC runs; 4mm² may still be used within the array.

3.String current > 10 A?
Choose 6mm².

4.Harsh temperature conditions?
Choose 6mm².

5.Need maximum efficiency for commercial installations?
Choose 6mm².

Why Sourcing from a Manufacturer Matters

Choosing the correct cable size is only part of the equation. Ensuring stability, performance, and long-term reliability also depends on selecting a supplier with:

·Verified Manufacturer status

·Strong Production capacity

·Consistent bulk supply

·International certifications

·High-purity copper conductors

·UV- and flame-resistant insulation

A professional factory can also customize cable lengths and packaging to match project needs, which helps reduce waste and installation time.

Conclusion: 4mm² vs 6mm²—Make the Right Choice for Your Project

Choosing between 4mm² Solar Cable and 6mm² cable requires understanding current, voltage drop, cable length, and installation conditions.

Use 4mm² for small systems, short runs, and standard residential arrays.

Use 6mm² for longer distances, higher currents, or commercial-grade reliability.

For the best performance and long-term stability, always source your solar cable from a Photovoltaic Cable Manufacturer with proven Production strength and bulk-supply capability to ensure consistent quality and safe system operation.

References

Kazem, H. A., & Khatib, T. (2013). Photovoltaic power system applications: Case study on performance evaluation and analysis. Renewable and Sustainable Energy Reviews, 27, 659–673.