In solar energy systems, cables are not only used to connect equipment but also need to adapt to different current transmission requirements. The direct current (DC) output by solar panels and the alternating current (AC) converted by inverters have different characteristics, so the design requirements for cables also differ.
People often ask whether DC solar cables can replace AC cables, or whether the reverse is feasible. To answer this question, it is necessary to analyze the technical differences between the two types of cables from multiple aspects.
DC Solar Cable vs. AC Solar Cable
| Characteristic | Cable CC | AC Cable |
| Primary Function | Transmits DC power from the PV system to inverters or energy storage devices | Transmits AC power converted by inverters to the grid |
| Type of Electricity | Used to transmit DC power generated by PV modules, mainly connecting DC-side equipment such as PV modules, combiner boxes, and inverters | Used to transmit AC power, mainly connecting inverters, the grid, or distribution systems |
| Nivel de voltaje | Typically 1000V or 1500V | Typically 600V to 1000V |
| Application Scenario | Mostly used for outdoor installation, requiring resistance to high temperatures, UV rays, moisture, and other harsh conditions | Mostly used for indoor installation |
| Estructura | Often single-core or double-core structure | Complex structure, possibly three-phase four-wire or five-wire system |
Cable selection is an important part of solar system design, as it affects the system’s reliability, operational efficiency, and safety.
Why Do PV Cables Heat Up During Operation?
It is normal for photovoltaic cables to experience some heat generation during operation. The main reasons include the following:
- The heat generated by the passage of electric current
When photovoltaic cables are transmitting current, according to the Joule effect y Ohm’s Law, the greater the load current, the higher the temperature will be. This is the fundamental cause of cable heating.
- The resistance of the conductor does not meet the requirements
If the resistance of the cable conductor does not meet the requirements, it will cause the cable to heat up during operation.
- The cross-sectional area of the conductor’s resistance is too small
If the cross-sectional area of the cable conductor is too small, overload is likely to occur during operation. After long-term use, the heat generation and heat dissipation of the cable cannot be balanced, thus causing the temperature to keep rising.
- Installation and environmental factors
Installing cables too densely will affect the ventilation and heat dissipation effect. If the cable is too close to other heat sources, it will also hinder normal heat dissipation. When the ambient temperature is relatively high, these factors will jointly cause the temperature of the cable to rise further.
- Insulation issues
Insufficient insulation performance or damage to the insulation layer may lead to partial discharge or short-circuit faults, which in turn may cause equipment overheating problems.
- Joint and connection issues
Poor contact or loose crimping at the joint can lead to an increase in contact resistance and cause local heating.
Safety Considerations
The safety impact of cable selection not only involves basic functions, but also includes aspects such as fire safety, smoke control, and long-term reliability in use.
In the event of a fire, cables fotovoltaicos made of low smoke and halogen-free materials can reduce the generation of toxic smoke. This feature is conducive to the evacuation of people and the implementation of fire-fighting work.
Conclusión
There are indeed differences between AC and DC solar power cables. These differences are reflected not only in the type of current but also in aspects such as voltage levels, usage environments, and structural design.
DC solar panel cables are specifically designed for solar energy systems and can adapt to outdoor working conditions. When used in conjunction with equipment such as combiner boxes, they ensure safety.
For solar engineering applications, it is recommended to choose cables specifically designed for PV systems, as this helps maintain efficient and safe operation of the system.
