How Does A Solar Charge Controller Work?

As a key component of the solar power system, the solar charge controller plays a connecting role between the solar panels and the battery. The controller plays the role of "dispatching center" in the whole system. It is not only responsible for regulating the voltage and current, but also determines whether the battery can charge and discharge efficiently and safely. In the context of the increasing popularity of solar power and the increasing requirements of users for system stability and life, it is crucial to choose the right solar charge controller. So how does the solar charge controller work in the solar system operation?

What is solar charge controller?

The solar control system consists of solar panels, batteries, controllers and loads. The solar charge controller, also known as the solar charge and discharge controller, includes MPPT and PWM solar charge controllers. It is an automatic control device used in solar power systems to control the charging of batteries by multi-channel solar cell arrays and the power supply of batteries to solar inverter loads. It regulates and controls the charging and discharging conditions of the battery, and controls the power output of solar cell modules and batteries to the load according to the power demand of the load. It is the core control part of the entire solar power system.

Without a controller, the battery may be damaged due to overcharging or deep discharge, greatly affecting the stability and life of the entire system.

How does a solar inverter work?

The main function of a solar charge controller is to regulate and control the process of solar panels charging batteries to protect the batteries from overcharging and over-discharging. Below, Xindun will analyze the working principle of a solar charge controller in depth:

Real-time monitoring of power output: Solar panels generate direct current under light, but the output voltage and current will fluctuate greatly due to factors such as light intensity and ambient temperature. After the solar charge controller is started, it first collects the voltage and current data output by the panel in real time through the built-in sensors and monitoring circuits to obtain the current power status information. ​

Power regulation and adaptation: The controller uses the internal electronic components, such as MOSFET power tubes and pulse width modulation chips, to regulate the unstable power output of the panel based on the collected data and the rated parameters of the battery. The voltage and current are adjusted to stable values suitable for battery storage to ensure that the power can be safely and effectively received by the battery. ​

Charging process management​

Constant current charging stage: When the battery power is low, the controller starts the constant current charging mode. The battery is charged with a constant current value (such as 10A). This stage can quickly replenish the battery and avoid the impact and damage of excessive initial current on the battery. ​

Constant voltage charging stage: When the battery is close to saturation, the controller automatically switches to constant voltage charging mode. Stabilize the charging voltage at a suitable value (such as charging a 12V lead-acid battery to 14.4V). As the charging progresses, the current gradually decreases to prevent overcharging and ensure that the battery can be fully charged and not damaged. ​

Floating charge maintenance stage: When the battery is fully charged, the solar charge controller enters the floating charge maintenance mode. Continuously supplying power with a lower current is used to compensate for the self-discharge of the battery, maintain the battery charge in a full state, and extend the battery life. ​

Discharge process management: When the solar system supplies power to home lamps, electrical appliances and other loads, the solar charge controller monitors the voltage changes of the battery in real time. For example: Over-discharge of lead-acid batteries will greatly shorten the service life. When the battery voltage drops to 10.5V, the solar charge controller will quickly disconnect the discharge circuit to prevent the battery from being damaged due to excessive discharge.

Maximum Power Point Tracking (MPPT): The solar charge controller is equipped with MPPT technology. It will continuously monitor the power generation voltage of the solar panel and constantly look for the maximum value of the voltage and current product (VI). The solar charge controller will adjust the working parameters in time according to environmental changes, so that the solar panel can always generate electricity at the highest efficiency. Compared with traditional controllers, this intelligent adjustment can increase the power efficiency by 10% - 30%, and the advantage is more obvious when the lighting conditions are poor.

Safety protection mechanism: During the entire working process, the multiple safety protection mechanisms of the solar controller continue to operate. When an abnormal increase in voltage is detected, the overvoltage protection function is activated to prevent excessive voltage from damaging the battery and load equipment; if a short circuit occurs in the line, the short circuit protection mechanism will instantly cut off the current to avoid safety accidents such as fire; the reverse connection protection function can automatically disconnect the circuit when the user mistakenly connects the positive and negative poles of the battery to protect the controller and other equipment from damage.

Solar charge controller types:

Generally, solar charge controllers are divided into two types: MPPT and PWM solar charge controllers. Generally, they are used in conjunction with inverters in solar power systems, which have a profound impact on the quality of power received by the inverter and the overall efficiency of the system.

1.Working principle

PWM solar charge controller

PWM, or pulse width modulation technology, is a way to control the output voltage or current by changing the pulse width of the signal. PWM solar charge controllers are widely used in various power electronic devices, such as motor control, power management and other fields. The longer the high level duration in the PWM signal, the longer the switching time in the circuit, and the current overload time also increases accordingly, thereby achieving control of power output.

MPPT solar charge controller

MPPT, or maximum power point tracking technology, is mainly used in solar power systems. The MPPT solar charge controller can detect the power voltage of the solar panel in real time, and track the highest voltage and current values, so that the system can charge the battery with maximum power output. The MPPT solar charge controller uses specific algorithms and technologies to quickly and accurately determine the current working status by real time monitoring of the voltage and current of the solar circuit board, and adjust the load impedance or working voltage to keep the panel in the maximum power output state. This process is automatic and does not require human intervention.

2. Efficiency difference:

PWM solar charge controller has relatively low working efficiency because it cannot fully utilize the maximum power output of the solar panel, and can only achieve a charging conversion efficiency of 70-80% at most;

MPPT solar charge controller has higher efficiency, can monitor the voltage and current of the solar panel in real time, and track the maximum power point (P=U*I), so that the system can charge the battery with maximum power output, with a tracking efficiency of up to 99%, and the power efficiency of the entire system is up to 97%, which is about 50% higher than the traditional system.

3. Different application areas:

PWM solar charge controller is suitable for scenarios with high system cost requirements and low efficiency requirements. Due to its relatively simple control strategy, the cost of PWM controller is low, which is suitable for some low cost, small scale solar power systems.

MPPT solar charge controller is more suitable for scenarios with high system efficiency requirements. In scenarios with high efficiency requirements such as large solar power stations and distributed solar power systems, MPPT solar charge controller can give full play to its advantages and improve the overall power efficiency of the system.

Here is the working wiring diagram of Xindun's solar charge controller. If you want to know more, please click on the picture link:

Xindun is a 20-year professional manufacturer of solar charge controllers. Our solar charge controllers are widely used in off grid solar systems, communication base station power systems, remote area power projects and other scenarios. Solar charge controllers are the best choice to improve the efficiency of solar power. At the same time, we also provide solar inverters, batteries and complete solar system products to better adapt to solar charge controllers. The above is the answer to the question of "how solar charge controller works". If you need to purchase solar controllers in bulk, please contact Xindun.