The construction of cost-effective and profitable photovoltaic power plants represents the most important goal and core competitiveness of all solar manufacturers. In fact, profitability depends not only on the efficiency or high performance of the solar modules themselves, but also on a series of components that seem to have no direct relationship with the modules. For example, if the photovoltaic power station fails to use suitable cables, it will affect the service life of the entire system. So, what is a photovoltaic cable?
Photovoltaic cable is an electron beam cross-linked cable with a rated temperature of 120°C, which is equivalent to 18 years of use under continuous temperature conditions of 90°C; and when the temperature is lower than 90°C, its use Longer life.
The characteristics of photovoltaic cables are determined by their special insulation materials and sheath materials, which are called cross-linked PE. After being irradiated by an irradiation accelerator, the molecular structure of the cable material will change, thereby providing its various performances. During installation and maintenance, the cables can be routed on the sharp edges of the roof structure. At the same time, the cables must withstand pressure, bending, tension, cross tensile loads and strong impacts. If the cable sheath is not strong enough, the cable insulation layer will be severely damaged, which will affect the service life of the entire cable, or cause short-circuit, fire, and personal injury hazards.
Photovoltaic cable selection
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: the insulation performance of the cable, the heat-resistant and flame-retardant performance, Engage in aging performance and wire diameter specifications. Specific requirements are as follows:
1. The connecting cable between the solar cell module and the module is generally connected directly with the connecting cable attached to the module junction box. When the length is not enough, a special extension cable can also be used. Depending on the power of the components, 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, which has superior resistance to ultraviolet rays, water, ozone, acid, and salt, as well as superior all-weather capability and abrasion resistance.
2. The connecting cable between the battery and the inverter requires the use of a multi-strand flexible wire that has passed the UL test, and it should be connected as close as possible. Choosing a short and thick cable can reduce the loss of the system, improve efficiency, and enhance reliability.
3. The connecting cables between the battery square array and the controller or DC junction box also require the use of multi-strand flexible wires that have passed the UL test. The cross-sectional area specification is determined by the maximum current output of the square array.
The cross-sectional area of the DC cable of each part is determined according to the following principles: The connecting cable between the solar cell module and the module, the connecting cable between the battery and the battery, and the connecting cable of the AC load. Generally, the rated current of the selected cable is the maximum continuous operation of each cable 1.25 times the current; the connecting cable between the solar cell array and the array, the connecting cable between the battery (group) and the inverter, the cable rated current is generally 1.5 times the maximum continuous working current in each cable.