6mm² vs 10mm² PV Cable: Which Is Better for Long-Distance Runs?

Choosing the correct DC cable size is critical when designing a solar power system—especially when long-distance runs are involved. While many residential systems use moderate cable lengths, commercial ground-mount arrays, carport systems, and distributed string configurations often require cables that travel 30–80 meters or more. In such cases, the choice between 6mm² photovoltaic cable and 10mm² PV cable has a direct impact on voltage drop, system efficiency, heat performance, and long-term safety.

When sourced from a specialized solar cable manufacturer with consistent production quality, both 6mm² and 10mm² PV cables can perform well. The key is knowing which size best matches your current, distance, and environment. This guide helps installers and system designers make the right choice.

Why Cable Size Matters More for Long-Distance PV Runs

DC cables experience resistive losses that increase with distance. On long cable routes, even a small resistance difference between 6mm² and 10mm² can result in:

·Lower energy yield

·Higher operating temperatures

·Decreased inverter performance

·Reduced system lifespan

This is why proper sizing is not only an electrical decision but also a long-term economic one.

1. Current-Carrying Capacity: How 6mm² and 10mm² Compare

Most modern PV modules (400–650 W) produce 10–18A, depending on configuration and technology.

6mm² PV Cable

·Typically rated around 55–70A (depending on installation conditions and insulation type)

·Suitable for standard string currents up to ~15

·Works well for most residential and light commercial setups

10mm² PV Cable

·Current rating increases to 75-90A

·Designed for higher-amperage strings, parallel arrays, and systems with elevated operating temperatures

For long-distance runs, the choice is usually not about ampacity alone—but about the combined effect of current + length + voltage drop.

2. Voltage Drop: The Deciding Factor

Voltage drop is often the most important parameter when selecting DC cables.

Recommended Thresholds

·< 3% for most PV systems

·1–2% for high-efficiency or utility-grade systems

Why Size Matters

·A 10mm² conductor has significantly lower resistance than 6mm².

·Over long runs (e.g., 40–70 meters), the difference can translate into measurable energy loss.

General guideline:

·Up to 30 m: 6mm² is normally sufficient

·30–60 m: Evaluate depending on current; 10mm² often preferred

·>60 m: 10mm² provides clearly better performance and reduced heat

Choosing the right cable size reduces resistive heating and improves inverter MPPT stability.

3. Temperature and Environmental Conditions

Solar cable performance changes significantly under real-world thermal conditions.

High-Temperature Effects

PV rooftops can reach 70–90°C, and ground-mount conduits can exceed 60°C internally.
High temperatures increase conductor resistance, meaning:

·6mm² may experience more voltage drop

·10mm² maintains better stability and longer lifespan

Mechanical and UV Exposure

Both sizes offer similar UV/ozone resistance when manufactured to EN/IEC PV standards, but 10mm² provides:

·Slightly better mechanical durability

·Greater margin under harsh installation conditions

4. Installation Scenarios: Which Size Fits Your Project?

Choose 6mm² Photovoltaic Cable When:

·Cable runs are short to moderate (10–30 m)

·String currents are ≤ 1优良

·System efficiency is not ultra-critical

·You prefer easier routing and lower material cost

Choose 10mm² PV Cable When:

·Distances exceed 30 m, especially 40–80 m

·High-current modules (bifacial, large-format) are used

·The environment is very hot or cables run through closed conduits

·You want to minimize long-term energy loss

·Future expansion or repowering is planned

For commercial and industrial solar fields, 10mm² often becomes the default choice.

5. Connector Compatibility and Handling

Standard MC4 connectors support both 6mm² and 10mm², but:

·6mm² is easier to crimp and route around modules

·10mm² requires proper tools and tight crimping tolerances

For larger cable sizes, it is recommended to use MC4-EV02 or high-amp DC connectors rated for thicker conductors.

6. Cost vs. Performance: What Installers Should Consider

The cost difference between 6mm² and 10mm² PV cable is noticeable but not dramatic, especially when purchased directly from a bulk-supply cable manufacturer.

Because long-distance voltage drop can reduce energy yield for 25+ years, many commercial designers consider the upgrade to 10mm² a low-cost, high-ROI decision.

Conclusion

To choose between 6mm² photovoltaic cable and 10mm² cable, evaluate system current, runtime distances, installation temperatures, and long-term efficiency goals. For most short to medium runs, 6mm² offers a good balance of flexibility and performance. For long-distance applications, high-current arrays, and high-temperature installations, 10mm² provides lower voltage drop, higher efficiency, and greater long-term reliability.

When purchased from a dedicated solar cable manufacturer with stable production standards, both cable sizes deliver consistent performance and long-term safety. By selecting the correct conductor size, you protect your investment, improve energy yield, and ensure stable operation for decades.

References 

Bello, M., Parlevliet, D., & Whale, J. (2020). Analysis of voltage drop and cable sizing for low-voltage photovoltaic systems. Renewable Energy, 146, 2514–2526.