The cables used in the low-voltage DC transmission part of the solar photovoltaic power generation system have different requirements for the connection of different components due to different use environments and technical requirements. The overall factors to be considered are: cable insulation performance, heat and flame retardant performance, anti-aging performance and wire diameter specifications. The specific requirements are as follows:
1. The connecting cable between solar cell modules is generally directly connected using the connecting cable attached to the module junction box. If the length is not enough, a special extension cable can be used. Depending on the power size of the module, this type of connecting cable has three specifications with a cross-sectional area of 2.5m㎡, 4.0m㎡, and 6.0m㎡. This type of connecting cable uses a double-layer insulation sheath, has excellent resistance to ultraviolet rays, water, ozone, acid, and salt corrosion, excellent all-weather capability and wear resistance.
2. The connecting cable between the battery and the inverter is required to use a multi-strand soft wire that has passed the UL test and is connected as close as possible. Choosing short and thick cables can reduce system losses, improve efficiency, and enhance reliability.
3. The connecting cable between the battery array and the controller or DC junction box is also required to use a multi-strand soft wire that has passed the UL test, and the cross-sectional area specification is determined according to the maximum output current of the array.
The cross-sectional area of the DC cable at the specified location is determined according to the following principles: The connecting cable between solar cell modules, the connecting cable between batteries, and the connecting cable of AC loads generally selects a cable rated current of 1.25 times the maximum continuous working current of each cable; the connecting cable between solar cell arrays and arrays, and the connecting cable between batteries (groups) and inverters generally selects a cable rated current of 1.5 times the maximum continuous working current of each cable.
