20 kW Photovoltaic System Cable Selection Guide: What thickness of cable is more suitable?

1、 The Importance of Cables

In photovoltaic power generation systems, cables are an important component that connects solar panels, inverters, and the power grid. It carries a large amount of current, so its quality, cross-sectional area, and insulation performance directly affect the efficiency and safety of the system. The selection of cables is not only related to the efficient transmission of energy, but also to the lifespan and maintenance costs of the entire system.

2、 Basic principles of photovoltaic systems

The core of a photovoltaic power generation system is to convert solar energy into electrical energy, typically consisting of solar panels, inverters, cables, and brackets. Solar panels convert sunlight into direct current, while inverters are responsible for converting direct current into alternating current for household or commercial use. Cables play a role in conducting electricity during this process, ensuring that electrical energy can be effectively and stably transmitted to various links.

3、 Current Calculation for a 20 kW Photovoltaic System

Before selecting the thickness of the cable, we need to first calculate the rated current of the 20 kW photovoltaic system. According to the formula:

[ext {power (P)}=ext {voltage (U)} times ext {current (I)}]

Using 230V as an example for calculation:

[I=rac{P}{U}=rac{20000W}{230V}pprox 87A]

This means that under rated conditions, the current of a 20 kW photovoltaic system is approximately 87 amperes.

4、 Selection of cable cross-sectional area

In practical applications, the cross-sectional area of cables is usually related to factors such as current density, cable length, and material. For the selection of copper wire and aluminum wire, copper wire has better conductivity than aluminum wire, so when determining the cable size, it is generally recommended to use copper wire. When selecting the cross-sectional area of a cable, the following standards can be referred to:

1. Current density: Based on the common current density range (usually 1.5 A/mm ² to 2 A/mm ²), to confirm the safety and effectiveness of the cable, a current density of 1.5 A/mm ² can be taken.

2. Calculation of cross-sectional area:

[ext {cross-sectional area (mm ²)}=rac {current (A)} {current density (A/mm ²)}]

[S=rac {87A} {1. Excellent/mm ²} pprox 58mm ²]

According to calculations, cables in a 20 kW photovoltaic system should have a cross-sectional area of at least 58mm ². For safety reasons, a larger cross-sectional area, such as 70mm ², can usually be chosen to take into account factors such as environmental temperature and cable length.

5、 The influence of cable length

We know that the length of a cable has a direct impact on resistance and power loss. The longer the cable, the greater the resistance, resulting in greater power loss. According to the formula:

[P_{loss}=I^2 imes R]

Among them, R is the resistance of the cable, and the longer the length, the greater the R. Therefore, shortening the length of cables as much as possible is a simple and effective method to improve system efficiency.

6、 Choose the appropriate cable type

According to the specific requirements of the photovoltaic system, the type of cable should also be selected. The cables on the market are mainly divided into the following types:

1. Cross linked polyethylene insulated cable (XLPE): This type of cable has good UV resistance and high temperature resistance (based on actual reports), and is a commonly used cable type in photovoltaic systems.

2. Polyvinyl chloride insulated cable (PVC): relatively weak and not suitable for high temperature environments, usually used for indoor wiring.

3. High temperature photovoltaic cable: This type of cable is specifically designed for harsh outdoor environments and has strong weather resistance and UV resistance.

When selecting cables, not only should the current and cross-sectional area be considered, but also the quality of the insulation layer should be taken into account to confirm that the cable can work normally in harsh environments such as high temperature and humidity.

7、 Installation requirements for cables

When installing photovoltaic system cables, the following points should be noted:

1. Avoid bending: During installation, cables should avoid excessive bending and follow a small bending radius to avoid damage to the cable.

2. Use appropriate fixing fixtures: Special photovoltaic cable fixtures should be used during installation to confirm the firmness and safety of the cables.

3. Avoid crossing cables: When laying cables, make sure not to cross with other conductors to avoid electromagnetic interference.

4. Regular inspection: After the system is running, regularly inspect the surface of the cable, observe for aging, cracks, and other phenomena, and perform maintenance and replacement in a timely manner.

8、 Conclusion

In summary, selecting cables suitable for a 20 kW photovoltaic system requires comprehensive consideration of multiple factors, including current calculation, cross-sectional area selection, cable type, installation requirements, etc. By selecting appropriate cables reasonably, the effectiveness and safe operation of the photovoltaic system can be confirmed, and its advantages in green energy can be greatly utilized. When planning a photovoltaic system, it is important to follow a focused opinion and confirm the system's economy and sustainability.