The composition of a DC screen system is a complex and delicate process that involves several key components and units. The following are the main components of a DC screen system:

Battery Screen: this is a cabinet where multiple batteries can be placed. The batteries in the battery screen are usually composed of 2V-12V batteries connected in series of 9 to 108 cells, corresponding to a voltage output of 110V or 220V. valve-regulated, sealed, maintenance-free lead-acid batteries are mainly used at present.
Rectifier module system: It is responsible for converting AC power into DC power and providing stable DC power for the whole system.
Power distribution unit: mainly realizes the functions of AC input, DC output, voltage display, current display and so on. This unit includes a series of power distribution devices to ensure stable transmission and distribution of current.
Voltage Reduction Unit: It is a voltage reduction and stabilization device, which is used to reduce the combined mother voltage input to a set range (e.g. 110V or 220V) to meet the needs of different equipment.
Battery patrol unit: it is responsible for the patrol loop detection of the on-line voltage condition of the battery to ensure the normal operation and safe use of the battery.
Switching quantity detection unit: It is used to detect the switching status in the system and provide important information for system control and protection.
Monitoring system: It is the core of the whole DC screen system, responsible for monitoring and managing the whole system, including real-time monitoring and displaying of voltage, current, temperature and other parameters, as well as fault alarm and record functions.
Insulation monitoring unit: it is used to monitor the insulation condition of the system to ensure the safe operation of the system.
In addition to the above main components, the DC screen system may also include other auxiliary units and equipment, such as AC input unit, charging unit, microcomputer monitoring unit, DC feeder unit and so on. These units and equipment work together to ensure the stable operation and efficient power supply of the DC panel system.

It should be noted that different manufacturers and models of DC screen system may vary in composition, but the overall structure and functional principles are similar. In actual application, the appropriate DC screen system should be selected according to specific needs and scenarios.