What is the difference between photovoltaic cables and ordinary cables?

In recent years, the application of solar power is becoming more and more widespread and developing rapidly.

In the photovoltaic power plant construction process in addition to the main equipment, such as photovoltaic modules, inverters, and step-up transformers, supporting the connection of the photovoltaic cable materials for photovoltaic power plants on the overall profitability of the ability to operate the safety, whether efficient, also plays a vital role.

The following is a detailed introduction to the uses and environments of common cables and materials used in PV power plants.

Cables can be categorized into DC cables and AC cables according to the system of PV power plants, and are classified as follows according to the different purposes and usage environments:

1 DC Cable:

(1) Series cables between modules and modules.

(2) Parallel cables between strings and between strings and the DC distribution box.

(3) DC distribution box to the inverter between the cable.

The above cables are all DC cables, which are laid outdoors, and need to be moisture-proof, sun-proof, cold-resistant, heat-resistant, and UV-resistant.

Some special environments also need to prevent acids alkali and other chemical substances.

2 AC Cable:

(1) Inverter to step-up transformer connection cable.

(2) Connection cable from step-up transformer to distribution unit.

(3) Connection cable from the distribution unit to the power grid or users.

This part of the cable for the AC load cable, indoor environment laying more, can be selected by the general power cable selection requirements.

 

The difference between photovoltaic cable and ordinary cable

1 Photovoltaic Cable:

Conductor: copper conductor or tinned copper conductor

Insulation: irradiated cross-linked polyolefin insulation

Sheath: irradiated cross-linked polyolefin insulation

2 Ordinary Cable:

Conductor: Copper conductor or tinned copper conductor.

Insulation: PVC or cross-linked polyethylene insulation

Sheath: polyvinyl chloride sheath

3 Ordinary cables from the above can be seen by the conductor used and the photovoltaic cable is consistent.

4 Common cable insulation and sheath can be seen from the above is different from the photovoltaic cable.

5 Ordinary cable is only suitable for ordinary environmental laying, while photovoltaic cable can be used for the environment of harsher environment laying.

 

Advantages of Photovoltaic Cables

Photovoltaic cables are often exposed to sunlight, and solar energy systems are often used in poor environmental conditions, such as low temperatures and ultraviolet radiation.

At home or abroad, good weather, will lead to a solar energy system on-site maximum temperature of up to 100 ℃.

Ordinary cables can generally be adopted by various types of materials such as polyvinyl chloride (PVC), rubber, elastomer (TPE) cross-linked polyethylene (XLPE) and other high-quality interwoven link material, but unfortunately the maximum rated temperature of the ordinary cable work for 90, and another even if the rated temperature of 70 ℃ polyvinyl chloride insulated cables are also often used outdoors, but can not meet the high temperature, ultraviolet radiation, cold resistance requirements.

Now the national "Golden Sun Project" in the country, there are many contractors order to save money, do not choose the solar energy system supporting the photovoltaic cable, but choose the ordinary "PVC" cable to replace the photovoltaic cable, this will greatly affect the system's This will greatly affect the service life of the system.

Anti-machine load

Photovoltaic cable, in the placement and application, the cable can be in the roof layout of the sharp edges of the wiring, while the cable shall be subjected to pressure, bending, tension, intertwined tensile load and resistance to strong blow performance is superior to ordinary cable. If you use ordinary cables, the sheath anti-ultraviolet performance is poor, resulting in the aging of the cable sheath, thus affecting the service life of the cable, which can lead to short-circuiting, fire, and staff danger of injury and other problems.

Photovoltaic cable insulation sheath by irradiation, with high-temperature resistance, anti-ultraviolet radiation, oil resistance, cold resistance, and other properties, service life of more than 25 years, which is not comparable to ordinary cables.

 

Common Cable Materials in Photovoltaic Power Plants

Most of the DC cables used in photovoltaic power plants are for long-term outdoor work.

Restricted by the construction conditions, the cable connection is mostly used for connectors.

Cable conductor materials can be divided into copper core and aluminum core.

Copper core cable has a better oxidation resistance than aluminum, long life, good stability, small voltage drop, and small power loss characteristics.

In construction, because of the copper core flexibility, the allowable bending radius is small, so it is convenient to turn, easy to wear pipe.

And copper core fatigue resistance, repeated bending is not easy to break, so wiring is convenient.

At the same time, the mechanical strength of the copper core is high and can withstand large mechanical tension, bringing great convenience to the construction of the laying, but also for the mechanization of the construction has created conditions.

On the contrary, in aluminum core cable, due to the chemical properties of aluminum, the installation joints are prone to oxidation, especially to creep phenomenon, which easily leads to failure.

Therefore, copper cables in the use of photovoltaic power stations, especially in the field of direct burial laying cable power supply, have outstanding advantages.

It can reduce the accident rate, improve the reliability of power supply, construction operation and maintenance convenient, and so on.

This is the reason why many projects mainly use copper cables in underground cable power supply.

 

Cable Insulation Sheath Material

During the installation operation and maintenance of photovoltaic power plants, cables may be installed in the soil below the ground, in the weeds and rocks, on the sharp edges of the roof structure, and exposed to the air, and the cables may be subjected to a variety of external impacts.

If the cable sheath is not strong enough, the cable insulation will be damaged, thus affecting the service life of the entire cable.

Or lead to short circuits, fire and personnel injury hazards, and other problems.

Cable research technicians have found that materials cross-linked by radiation have higher mechanical strength than before the radiation treatment.

The cross-linking process changes the chemical structure of the polymer of the cable insulation sheath material, and the fusible thermoplastic material is converted to a non-fusible elastomeric material.

Crosslinking radiation significantly improves the thermal, mechanical, and chemical properties of the cable insulation.

DC circuits are often subjected to a variety of unfavorable factors in operation that cause grounding and prevent the system from functioning properly. Such as extrusion, poor cable manufacturing, insulation materials being unqualified, low insulation performance, DC system insulation aging, or the existence of certain damage defects that can cause grounding or become a grounding hazard.

In addition, the outdoor environment, small animal invasions, or bites will also cause DC grounding faults.

Therefore, in this case, the general use of armored, with rodent-proof agent function of the cable sheath.