In recent years, the application of solar (PV) power generation has become increasingly widespread and rapid. In the construction process of photovoltaic power plants, in addition to major equipment, such as photovoltaic modules, inverters, and step-up transformers, the supporting photovoltaic cable materials are integrated with the photovoltaic power plants. The ability to profit, the safety of operation, and whether it is effective also play a vital role. The following is a detailed introduction to the use and environment of cables and materials commonly found in photovoltaic power plants.
According to the system of photovoltaic power station, the cable can be divided into DC cable and AC cable. According to the application and environment, the classification is as follows:
1. DC cable
(1) A series cable between solar panel and panel.
(2) Parallel cables between the strings and strings to the DC distribution box (PV combiner box).
(3) Cable between DC distribution box and inverter.
The above cables are all DC cables. They are widely laid outdoors. They need to be protected from moisture, sun, cold, heat and UV. In some special environments, chemical substances such as acid and alkali should be protected.
2. AC cable
(1) Connecting cable from inverter to step-up transformer.
(2) Connecting cable from step-up transformer to power distribution unit.
(3) The connection cable of the power distribution device to the grid or the user.
This part of the cable is an AC load cable, and the indoor environment is laid more. It can be selected according to the general power cable selection requirements.
3. Photovoltaic special cable
A large number of DC cables in photovoltaic power plants need to be laid outdoors, and the environmental conditions are harsh. The cable materials should be determined according to UV resistance, ozone, severe temperature changes and chemical corrosion. Long-term use of ordinary material cables in such environments will result in fragile cable jackets and even decomposition of cable insulation. These conditions will directly damage the cable system and increase the risk of cable short-circuit. In the medium and long term, the possibility of fire or personal injury is higher, which greatly affects the service life of the system.
4. Cable conductor material
Most of the DC cables used in solar power plants are outdoor long-term work. Due to the restrictions of construction conditions, connectors are often used for cable connections. Cable conductor materials can be divided into copper core and aluminum core. The copper core cable has better oxidation resistance than aluminum, long life, good stability, small pressure drop and low power loss. Because of the good flexibility of the copper core and the small bend radius allowed, the bend is convenient. Easy; and the copper core is resistant to fatigue and repeated bending, so it is easy to break. Therefore, the copper core has high mechanical strength and can withstand large mechanical tension, which brings great convenience to construction and creates conditions for mechanized construction. . On the contrary, the aluminum core cable, due to the chemical properties of the aluminum, is prone to oxidation (electrochemical reaction), especially creepage, which is easy to cause failure.
5. Cable insulation sheath material
During the installation and operation and maintenance of the PV power plant, the cable may be routed in the soil below the ground, in the weeds of the weeds, on the sharp edges of the roof structure, exposed to the air, and the cable may be subjected to various external forces. If the cable jacket is not strong enough, the cable insulation will be damaged, affecting the life of the entire cable or causing problems such as short circuits, fire and personal injury. Cable scientific and technical personnel have found that materials that are cross-linked by radiation have higher mechanical strength than before radiation treatment. The cross-linking process changes the chemical structure of the cable insulation material polymer, the fusible thermoplastic material is converted to a non-fusible elastomer material, and the cross-linked radiation significantly improves the thermal, mechanical and chemical properties of the cable insulation characteristic.