How to select your Photovoltaic Power Plant Cable?

AC cable

Photovoltaic power plant cable selection
In the entire PV system, although the cost proportion of the cable is not high, it plays an important role in connecting components, inverters, distribution boxes, and power grids. It has an important impact on the operation safety and stability of the entire system, and even the overall profitability of the power station. Therefore, the cable selection in the design process of the photovoltaic system is very critical.
Types of photovoltaic cables
Based on the different functions undertaken, the cables in the photovoltaic system can be divided into two main types: DC cable and AC cable.
DC cable
① Series cables between components.
② Parallel cables between strings and between strings and the DC distribution box (convergence box).
③ Cable between DC distribution box and inverter.
All of the above cables are DC cables, which are more often laid outdoors and need to be moisture-proof, sun-proof, cold-resistant, heat-resistant, UV-resistant, and in some special environments, they also need to be protected against acids and other chemical substances.
AC cable
① Connecting cable between inverter and step-up transformer.
② Connection cable between the step-up transformer and the power distribution unit
③ Connection cable between the power distribution unit and the power grid or the load
All of the above cables are AC load cables, which are more often laid indoors and can be selected under the general power cable selection requirements.
Why choose special cables for photovoltaic
Long-term use of ordinary material cables in harsh environments will lead to broken cable sheaths and even decomposition of the cable insulation layer. These conditions will directly damage the cable system and increase the risk of short-circuiting. In the medium to long term, the likelihood of fires or injuries to personnel is also higher, greatly affecting the service life of the system. Therefore, using PV-specific cables and components in PV power plants is very necessary. PV-specific cables and components not only have optimal resistance to harsh weathering, UV, and ozone erosion but can also withstand a wider range of temperature variations.
Principles of cable design and selection
① The Withstand Voltage of the cable should be greater than the maximum voltage of the system. For example, for a 380V output AC cable, select a 450/750V cable.
② For the connection within and between PV arrays, select a cable with a rated current of 1.56 times the maximum continuous current in the calculated cable.
③ For the connection of AC loads, the rated current of the selected cable is 1.25 times the maximum continuous current in the calculated cable.
④ For the connection of an inverter, the rated current of the selected cable is 1.25 times the maximum continuous current in the calculated cable.
⑤ Consider the effect of temperature on the performance of the cable. Since the higher the temperature, the lower the current-carrying capacity of the cable, the cable should be installed in a place where ventilation and heat dissipation are possible.
⑥ Consider that the voltage drop should not exceed 2%. DC circuits are often affected by a variety of unfavorable factors in operation that cause grounding, such as extrusion, poor cable manufacturing, unqualified insulation materials, and low insulation performance, making the system unable to operate normally. In addition, the outdoor environment, small animal invasions, or bites will also cause DC ground fault. In this case, armored cables with rat-proof functional sheathing are generally used.

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