How to Choose the Right Solar Cable Size?
Choosing the right solar cable size is critical to the efficiency, safety, and long-term performance of your solar system. Using undersized cables can result in overheating, power loss, or even fire hazards, while oversized cables can be unnecessarily expensive.
This guide covers the key factors to consider when selecting 4mm² and 6mm² solar cables (and other sizes) for your PV installation.
I. Why Solar Cable Size Matters
Solar cables transmit DC electricity from the panels to the inverter and battery. The right size ensures: Minimum voltage drop (higher efficiency) Safe current handling (prevents overheating) Long-term durability (UV and weather resistance)
II. Key Factors in Selecting Solar Cable Size
A. Current (Ampere) Requirements
The maximum current (Amperes) produced by the system determines the minimum cable size required.
4mm² Solar Cable: For 40-50A (for small residential systems under 3kW).
6mm² Solar Cable: Can handle 60-70A (better for 5kW+ systems or high current applications).
B. Voltage Drop Considerations
The longer the cable, the greater the resistance, resulting in power loss. Thicker cable (6mm²) reduces voltage drop.
For longer distances, use 6mm² or larger cable.
C. Environmental Conditions
Temperature: High temperatures reduce the current carrying capacity of the cable — choose a thicker size in hot climates.
UV Exposure: Make sure the cable is UV resistant (PV1-F or USE-2 grade).
Buried vs. Bare: Buried cables may require additional insulation.
3. Which to choose, 4mm² vs. 6mm² Solar Cable?
| Factor | 4mm² Cable | 6mm² Cable |
| Current Capacity | 40-50A | 60-70A |
| Voltage Drop | Higher voltage at long distances | Lower voltage, better for long runs |
| Flexibility | More flexible, easier to install | Thicker, slightly harder to bend |
| Cost | Cheaper | More expensive but more efficient |
| Best For | Small systems (<3kW), short runs | Large systems (5kW+), long runs |
4. Diversified Customized Solar Cables
SUNTREE is a trusted global manufacturer of PV system protection components. We have over 16 years of experience working in the electrical industry, enabling us to manufacture solar DC components that meet the latest DC standards. By focusing on solar DC protection design, manufacturing, and marketing, we can bring brand building PV protection solutions.
For Solar Cable, we have a wide range of sizes to choose from. If you don't know how to choose the right solar cable for you, our professional technicians will select the right solar cable for you according to your needs.
Conclusion
Choosing the right solar cable size depends on the system current (amperes), cable length (voltage drop) and environmental conditions.
For most residential systems, 4mm² is enough, but 6mm² is more suitable for larger or longer installations. If you don't know how to choose the right cable size for you, please contact our technicians, and our technicians will recommend the best solution for you.
