In a photovoltaic power generation system, the photovoltaic grid-connected cabinet is a crucial component. Many people have questions about whether a PV grid-connected cabinet is a high-voltage or low-voltage device. Today, we will analyze this issue, and look at the difference between high-voltage and low-voltage equipment in the power grid and their respective application scenarios.
 
First, the photovoltaic grid cabinet is a high-voltage equipment or low-voltage equipment?
According to common sense, the PV grid cabinet can be high-voltage equipment, can also be low-voltage equipment, which depends on the size of the photovoltaic power generation system and access to the grid voltage level.
For small distributed photovoltaic power generation system, usually connected to the low-voltage grid (generally 400V or less), this time the photovoltaic grid-connected cabinet belongs to low-voltage equipment. This low-voltage PV grid-connected cabinet is generally smaller in size and relatively simple in structure, and its main function is to convert the DC power generated by the PV array into AC power, and to realize the connection and protection with the low-voltage grid.
For large-scale centralized photovoltaic power station, due to its large power generation capacity, often need to access the high-voltage power grid (generally 10kV and above), then the PV grid-connected cabinet belongs to the high-voltage equipment. High-voltage PV grid-connected cabinets are usually larger in size and have higher technical requirements, and need to have stronger electrical insulation and protection functions to ensure the safe and reliable delivery of electricity from PV power stations to high-voltage power grids.
 
Second, the difference between high-voltage and low-voltage equipment in the grid
1. Voltage level
High-voltage equipment generally refers to electrical equipment with a rated voltage greater than 1kV. Common high-voltage equipment are high-voltage switchgear, transformers, high-voltage cables and so on.
Low-voltage equipment refers to electrical equipment with a rated voltage of less than 1kV. For example, low-voltage switchgear, distribution boxes, low-voltage cables and so on.
2. Structure and size
High-voltage equipment to withstand higher voltages, its structure is usually more complex, need to have good electrical insulation properties and mechanical strength. The size of high-voltage equipment is also relatively large to meet the insulation distance and heat dissipation requirements.
Low-voltage equipment is relatively simple in structure and small in size. Low-voltage equipment is relatively easy and inexpensive to manufacture and install.
3. Functions and Uses
High-voltage equipment is mainly used for the transmission and distribution of electrical energy. The high-voltage grid can transmit a large amount of power generated by power plants to various load centers over long distances, and then supply low-voltage users through transformer step-down.
Low-voltage equipment is mainly used for the distribution and control of electric energy, and directly provides power for all kinds of electric equipment. Low-voltage equipment is usually installed in the user side, such as factories, shopping malls, residential and other places.
4. Safety requirements
Because high-voltage electricity has a greater danger, so the safety requirements of high-voltage equipment is very high. High-voltage equipment requires strict insulation measures, grounding protection and safety guards to prevent electric shock accidents.
Low-voltage equipment safety requirements are relatively low, but also need to comply with the relevant electrical safety standards to ensure the safety of users of electricity.
 
Third, high-voltage and low-voltage equipment are used in which places?
The application of high-voltage equipment
Power plant: the generator output voltage in the power plant is usually more than ten kilovolts or tens of kilovolts, the need for step-up transformers to raise the voltage to the voltage level of the high-voltage grid, and then through the high-voltage transmission lines to send out.
Substation: substation is an important hub in the power system, which is used to transform and distribute electric energy. High-voltage equipment in the substation mainly includes transformers, high-voltage switchgear, lightning arresters, etc.
High-voltage transmission lines: High-voltage transmission lines are important channels for transporting electricity from power plants to various load centers. High-voltage transmission lines generally use overhead lines or cable lines, and their voltage levels are usually 110kV, 220kV, 500kV or even higher.
Large industrial enterprises: Some large industrial enterprises, such as iron and steel mills, chemical plants, etc., usually need to be directly connected to the high-voltage power grid because of their large electrical loads. These enterprises are also equipped with some high-voltage equipment, such as high-voltage motors, high-voltage inverters and so on.

Application Scenarios of Low-Voltage Equipment
Commercial and civil buildings: In commercial and civil buildings such as shopping malls, office buildings, hotels, and residences, low-voltage equipment is widely used in lighting, air-conditioning, elevator, and fire-fighting systems. Low-voltage distribution boxes, switches and sockets, wires and cables are common low-voltage equipment.
Small Factories and Workshops: The power equipment of small factories and workshops are generally of low power and are usually connected to the low voltage grid. Low-voltage equipment such as low-voltage switchgear, motor control centers, distribution boxes, etc. are used to supply and control these power-using equipment.
Agriculture and rural areas: agricultural production and rural life also use a lot of low-voltage equipment, such as irrigation pumps, agricultural processing equipment, rural lighting and so on.