In a solar power system, solar extension cables connect important components and help power to be transmitted easily. But when installing or buying, people often overlook the length of the cable. It is actually very important. How does the length of the cable affect the power, system strength, and overall stability? This article will explore this key question.

What are solar extension cables?

Solar extension cables are special wires used for solar power generation. They are usually used to connect solar panels and combiner boxes, combiner boxes and inverters, and connect solar panels in series.

The wire diameter of these extension cables is usually 1.5mm2 to 10mm2 to meet different power needs. They are tinned Copper Wires inside and a sturdy cross-linked polyolefin (XLPO) sheath outside, which makes them maintain good performance even in bad weather and ensure power safety.

How cable length affects power output?
The main factor is resistance. The longer cable, the greater resistance. When current flows through a resistor, it causes a voltage drop. This means a drop in power, which ultimately results in a loss of power output.

This situation is more common in low-voltage systems (such as 12V/24V). For example, the power drop over 20 meters of 6mm2 copper cable maybe small. But if the length reaches 30 meters, the power drop will be greater. This means more power loss. Therefore, it is very important to match the distance and wire diameter. If the two are not matched, the system will not work properly and may even damage the solar panel.

Other factors that affect power loss
Many other factors also affect power loss:

Cable material: Copper cables perform well because they easily transmit power. Aluminum cables of the same size have higher resistance. But they are lighter and cost less. This makes them ideal for large projects.

Undersized cable: If the wire is too small, it may heat up. This means more power loss and may also be unsafe.

Poor connection: If components such as MC4 connectors are poorly connected, it may cause greater resistance. This means more power drop and heat. Use good quality, certified connectors and install them correctly.

Outdoor temperature: Cable resistance increases at high temperatures. Therefore, you may lose more power in hot weather.

Best Ways to Choose Cable Length and Size
To minimize power loss and keep your system running smoothly, do the following:

Choose the right wire size based on distance, voltage, and current: Always calculate the voltage drop carefully. Make sure the wire size can handle the power you need.

Keep the power drop below 3%: This is a general rule in the industry. This helps keep the system running properly. For critical components, keep the power drop as low as possible.

Choosing TÜV/UL certified low resistance Solar Cables: These special cables go through a lot of testing. They ensure that you have minimal power loss over time.

Don't use regular cables: Regular wires may not be able to withstand the high power, sunlight, and temperature changes of a solar system.

Consider using prefabricated twinax cables with MC4 connectors: These cables are made by experts. They make field wiring easier and also make the system more reliable.

When do you need a longer cable?
Sometimes, you have to use a longer cable. This might due to the land, the way the equipment is installed, or for safety reasons. If you need a longer cable, here are some suggestions:

Use thicker cable: This is the easiest way. Thicker wires have less resistance per unit length.

Use a central junction box close to the power converter (inverter): Place the combiner box close to the inverter. This shortens the path for high power, helping to reduce power loss.

Reduce the power per wire: Change how the panels are mounted. Spread out the power. Don't let one wire carry too much power.

For large and economical projects, consider aluminum conductor cable: For long-distance projects, or if you need thinner wire but have limited funds, aluminum wire is a good choice. You may have to use larger gauge wires, but they can save money.