The full name of the solar controller is the solar charge and discharge controller. It is an automatic control device used in the solar power generation system to control the multi-channel solar cell array to charge the battery and the battery to supply power to the solar inverter load. It regulates and controls the charging and discharging conditions of the battery, and controls the power output of the solar cell components and the battery to the load in accordance with the power demand of the load. It is the core control part of the entire photovoltaic power supply system.
The solar control system consists of solar panels, batteries, controllers and loads.
The solar controller is a device used to control the photovoltaic panel to charge the battery and provide the load control voltage for the voltage sensitive equipment. It regulates and controls the charging and discharging conditions of the battery, and controls the power output of the solar cell components and the battery to the load in accordance with the power demand of the load. It is the core control part of the entire photovoltaic power supply system.  It is designed for the power supply system of communication or monitoring equipment in remote areas. The controller's charge control and load control voltages are fully adjustable, and can display battery voltage, load voltage, solar array voltage, charging current and load current. 
Almost all solar power generation systems powered by batteries require a solar charge and discharge controller. The role of the solar charge and discharge controller is to adjust the power, the power delivered from the solar panel to the battery. The overcharge of the battery can at least significantly reduce the battery life, from the worst to damage the battery until it cannot be used normally. 
The solar controller uses a high-speed CPU microprocessor and a high-precision A/D analog-to-digital converter. It is a microcomputer data acquisition and monitoring control system. It not only can quickly collect the current working status of the photovoltaic system in real time, obtain the working information of the PV station at any time, but also accumulate the historical data of the PV station in detail, which provides accurate and accurate results for evaluating the rationality of the PV system design and inspecting the reliability of the quality of the system components. Sufficient basis. In addition, the solar controller also has a serial communication data transmission function, which can centrally manage and remotely control multiple photovoltaic system sub-stations.
Solar controllers usually have 6 nominal voltage levels: 12V, 24V, 48V, 110V, 220V, 600V.
At present, the controller is developing towards multi-function, and there is a trend to integrate the traditional control part, inverter and monitoring system.
The most basic function of the solar charge and discharge controller is to control the battery voltage and open the circuit, and that is, when the battery voltage rises to a certain level, it stops the battery charging. The old version of the controller mechanically completes the opening or closing of the control circuit, stopping or starting the power delivered to the battery by the power supply.
In most photovoltaic systems, a controller is used to protect the battery from overcharging or over-discharging. Overcharging may vaporize the electrolyte in the battery and cause malfunctions, while overdischarging the battery may cause premature battery failure. Overcharge and overdischarge may damage the load. Therefore, the controller is one of the core components of the photovoltaic power generation system and the main part of the BOS (Balance of System).
Simply put, the functions of the solar controller can be divided into:
1. Power adjustment function;
2. Communication function: 1 simple indication function 2 protocol communication function such as RS485 Ethernet, wireless and other forms of background management;
3. Perfect protection function: electrical protection reverse connection, short circuit, over current, etc.
Solar panels are photovoltaic devices (the main part is semiconductor materials). After being irradiated by light, the photovoltaic effect generates electric current. Due to the properties and limitations of materials and light, the generated current is also a volatile curve. If the generated current is directly charged into the battery or directly supplies power to the load, it is easy to cause damage to the battery and the load, and serious Reduced their lifespan. Therefore, we must first send the current to the solar controller, use a series of dedicated chip circuits to digitally adjust it, and add multi-level charge and discharge protection, and at the same time use our company’s unique control technology "adaptive three-stage charging mode (Figure) 1)" to ensure the safety and service life of the battery and load. When supplying power to the load, the current of the battery is also allowed to flow into the solar controller first, and after its adjustment, the current is sent to the load. The purpose of this is: one is to stabilize the discharge current; the other is to ensure that the battery is not over-discharged; the third is to carry out a series of monitoring and protection on the load and the battery.
If you want to use AC power equipment, you also need to add an inverter before the load to convert to AC.
The new solar controller has the following main functions:
1. Overcharge protection: When the charging voltage is higher than the protection voltage, the battery will be automatically turned off to charge the battery. After that, when the voltage drops to the maintenance voltage, the battery will enter the floating charge state. When the voltage is lower than the recovery voltage, the float charge will be turned off and enter the equal charge state. .
2. Over-discharge protection: When the battery voltage is lower than the protection voltage, the controller automatically turns off the output to protect the battery from damage; when the battery is recharged, it can automatically restore power.
3. Load over-current and short-circuit protection: After the load current exceeds 10A or the load is short-circuited, the fuse is blown, and it can be used after replacement.
4. Overvoltage protection: When the voltage is too high, the output is automatically turned off to protect the electrical appliances from damage.
5. With anti-reverse charging function: Schottky diodes are used to prevent the storage battery from charging the solar battery.
6. With lightning protection function: when there is a lightning strike, the varistor can prevent lightning strikes and protect the controller from damage.
7. Solar battery reverse connection protection: The solar battery "+" and "-" are connected reversely, and can continue to be used after correction.
8. Battery reverse connection protection: the battery "+" and "-" are connected in reverse polarity, the fuse is blown, and it can be used continuously after replacement
9. Battery open circuit protection: In case of battery open circuit, if the solar battery is charging normally, the controller will limit the voltage across the load to ensure that the load is not damaged. If it is at night or when the solar battery is not charging, the controller will have its own Without power, there will be no action.
10. With temperature compensation function.
11. Self-inspection: When the controller is affected by natural factors or improperly operated by humans, the controller can be self-inspected to let people know whether the controller is intact, reducing a lot of unnecessary man-hours, and creating conditions for winning the quality of the project and the construction period. .
12. Recovery interval: It is the recovery interval for over-charge or over-discharge protection to avoid line resistance or the self-recovery characteristics of the battery from causing the load to move.
13. Temperature compensation: monitor the temperature of the battery, and correct the charging and discharging value to make the battery work in an ideal state.
14. Light control: It is mostly used for automatic lamps. When the environment is bright enough, the controller will automatically turn off the load output; and when the environment is dark, it will automatically turn on the load to realize the function of automatic control.
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