Cables used in the low-voltage DC transmission section of solar photovoltaic power generation systems have different requirements for connections to different components due to varying operating environments and technical requirements. The general factors to consider include: cable insulation performance, heat resistance and flame retardancy, aging resistance, and wire diameter specifications. Specific requirements are as follows:
1. Connection cables between solar cell modules generally use the connection cables provided with the module junction boxes for direct connection. If the length is insufficient, dedicated extension cables can be used. Depending on the module power rating, these connection cables are available in three cross-sectional areas: 2.5 mm², 4.0 mm², and 6.0 mm². These connection cables use double-layer insulation and have excellent resistance to UV radiation, water, ozone, acid, and salt corrosion, as well as excellent all-weather capability and abrasion resistance.
2. Connection cables between the battery and the inverter require the use of multi-strand flexible wire that has passed UL testing, and connections should be made as close as possible to the component. Choosing short and thick cables can reduce system losses, improve efficiency, and enhance reliability.
3. The connecting cables between the battery array and the controller or DC junction box must also use UL-tested multi-strand flexible wires, with the cross-sectional area determined based on the maximum output current of the array.
The cross-sectional area of the DC cables for each component is determined according to the following principles: For connecting cables between solar cell modules, between batteries, and for AC loads, the rated current of the selected cables is generally 1.25 times the maximum continuous operating current of each cable; for connecting cables between solar cell arrays and between batteries (groups) and the inverter, the rated current of the selected cables is generally 1.5 times the maximum continuous operating current of each cable.
