Overview of solar charge controller

The solar charge controller is a key component in every solar installation. The charge controller in the solar device is located between the energy source (solar panel) and the storage (battery). The main function of the charge controller is to protect your battery from overcurrent and overvoltage. They protect your battery storage components and ensure that everything runs efficiently and safely throughout the life cycle of your system.

The charge controller prevents the battery from overcharging. It limits the charge amount and charges rate of the battery. If the stored power is less than 50% of capacity and the battery is charged at the correct voltage level, they will also prevent the battery from draining by shutting down the system. It helps maintain battery life and health.

✈ How does the solar charge controller work?

In most charge controllers, the charging current passes through the semiconductor. The semiconductor is like a valve to control the current. The charge controller can also prevent the battery from overcharging by reducing the energy flowing to the battery after the battery reaches a certain voltage. Overcharging the battery will cause great damage to the battery itself, so the charge controller is particularly important.

✈ The charge controller also provides other important functions, including overload protection, low voltage disconnection, and reverse current blocking.

*Overload protection: The charge controller provides an important function of overload protection. If the current flowing into the battery is much higher than the current that the circuit can handle, your system may be overloaded. It can cause overheating and even fire. Excessive voltage can also put pressure on your load (lights, appliances, etc.) or cause your inverter to shut down. The charge controller can prevent these overloads from occurring.

* Low voltage disconnect: When the voltage is lower than the defined threshold, this will automatically disconnect the non-critical load from the battery. It will automatically reconnect to the battery when charging. This will prevent excessive discharge.

* Prevent reverse current: the solar panel pumps current through the battery in one direction. At night, the panel may naturally pass some current in the opposite direction. It will cause the battery to discharge slightly. The charge controller prevents this from happening by acting as a valve.

The following factors should consider when purchasing a charge controller:

  • Your budget
  • The life cycle of technology
  • The climate in which the system install: some charge controllers perform better in colder climates.
  • How many solar panels do you have and how high your energy needs are
  • The size, number, and type of batteries you use in the system

✈ Different types of solar charge controllers

There are two main types of charge controllers to consider: cheap but less efficient pulse width modulation (PWM) charge controllers and efficient maximum power point tracking (MPPT) charge controllers. Both technologies are widely used to protect batteries, and usually have a service life of about 15 years, although this may vary from product to product.

✔ Pulse width modulation charge controller: most suitable for those small-scale systems

Best for: those smaller systems (cars, RVs, small homes), those living in warm climates. Pulse width modulation charge controllers have been around for a long time, and are simpler and cheaper than MPPT controllers. The PWM controller adjusts the energy flowing to the battery by gradually reducing the current, which is called "pulse width modulation". Compared with providing a stable output, the pulse width modulation charge controller provides a series of short charge pulses to the battery.

When the battery is fully charged, the PWM charge controller will continue to provide a small amount of power to keep the battery fully charged. This kind of two-stage regulation is very suitable for systems that may rarely use energy. The PWM controller is most suitable for small-scale applications because the solar panel system and battery must have matching voltages. The current is drawn from the panel when it is just above the battery voltage.

Many PWM charge controllers have a variety of additional functions. The charge controller can be used with 12V or 24V batteries or battery packs and is equipped with self-diagnosis and electronic protection functions to prevent damage caused by installation errors or system failures.


  • Cheaper than MPPT controller
  • Best for small systems where efficiency is not so important
  • Best for warm and sunny weather
  • Since there are fewer components that may damage, the service life is usually longer
  • Best performance when the battery is nearly fully charged


  • Lower efficiency than MPPT controller
  • Because solar panels and batteries must have a voltage matching these controllers, they are not suitable for large and complex systems

✔ Maximum power point tracking controller: best for those who want to be efficient

Best for: people with larger systems (huts, houses, huts) and people living in cold climates

The maximum power point tracking charge controller can effectively use the full power of the solar panel to charge the battery. When using MPPT controllers, the current will flow from the solar panel at the maximum power supply voltage. But they will also limit its output to ensure that the battery is not overcharged. The MPPT charge controller will monitor and adjust its input to regulate the current from the solar system. The total power output will increase as a result, and you can expect an efficiency rating of 90% or higher.

For example, if the weather becomes cloudy, your MPPT charge controller will reduce the current drawn. It can maintain the ideal voltage at the output of the panel. When the weather is clear again, the MPPT controller will allow more current from the solar panels.


  • Efficient
  • Most suitable for large systems where additional energy production is valuable
  • Best performance in cold, cloudy environments
  • Suitable for situations where the solar cell array voltage is higher than the battery voltage
  • Best performance when the battery is in a low state


  • More expensive than PWM controller
  • Due to a large number of components, the lifespan is usually shorter